Merge #7062

7062: Remove version overwriting hacks r=deivid-rodriguez a=deivid-rodriguez

### What was the end-user problem that led to this PR?

The problem was that we are doing some hacks in our version file that are... dangerous. At very least they cause "circular problems" like #6927, but I also have bad feelings about it.

### What was your diagnosis of the problem?

My diagnosis was we're overwriting the version of the currently loaded bundler :grimacing:. This hack is _almost_ unnecessary (see the spec run here with the hack fully removed: https://travis-ci.org/bundler/bundler/builds/509497021. Only three jobs failed, and for old rubies/rubygems/bundler). 

### What is your fix for the problem, implemented in this PR?

My fix is to limit the hack to `bundler`'s spec run, since it's only needed there.

### Why did you choose this fix out of the possible options?

I chose this fix because fully getting the build green with the hack fully removed is a bit of work. I dedicated a bit of time to investigate one of the failures and it all comes down to the priority of loading default gems vs `-I`. So I think something like https://github.com/rubygems/rubygems/pull/1868 should fix it. But that's out of the scope of this PR.

Closes #6927.

Co-authored-by: David Rodríguez <deivid.rodriguez@riseup.net>

30 files changed, 100 insertions, 113 deletions

diff --git a/lib/bundler.rb b/lib/bundler.rb
index 8ad5ab6634..d8f9462c6d 100644
--- a/lib/bundler.rb
+++ b/lib/bundler.rb
@@ -22,43 +22,43 @@ module Bundler
   ENV.replace(environment_preserver.backup)
   SUDO_MUTEX = Mutex.new
 
-  autoload :Definition,             "bundler/definition"
-  autoload :Dependency,             "bundler/dependency"
-  autoload :DepProxy,               "bundler/dep_proxy"
-  autoload :Deprecate,              "bundler/deprecate"
-  autoload :Dsl,                    "bundler/dsl"
-  autoload :EndpointSpecification,  "bundler/endpoint_specification"
-  autoload :Env,                    "bundler/env"
-  autoload :Fetcher,                "bundler/fetcher"
-  autoload :FeatureFlag,            "bundler/feature_flag"
-  autoload :GemHelper,              "bundler/gem_helper"
-  autoload :GemHelpers,             "bundler/gem_helpers"
-  autoload :GemRemoteFetcher,       "bundler/gem_remote_fetcher"
-  autoload :GemVersionPromoter,     "bundler/gem_version_promoter"
-  autoload :Graph,                  "bundler/graph"
-  autoload :Index,                  "bundler/index"
-  autoload :Injector,               "bundler/injector"
-  autoload :Installer,              "bundler/installer"
-  autoload :LazySpecification,      "bundler/lazy_specification"
-  autoload :LockfileParser,         "bundler/lockfile_parser"
-  autoload :MatchPlatform,          "bundler/match_platform"
-  autoload :ProcessLock,            "bundler/process_lock"
-  autoload :RemoteSpecification,    "bundler/remote_specification"
-  autoload :Resolver,               "bundler/resolver"
-  autoload :Retry,                  "bundler/retry"
-  autoload :RubyDsl,                "bundler/ruby_dsl"
-  autoload :RubyGemsGemInstaller,   "bundler/rubygems_gem_installer"
-  autoload :RubyVersion,            "bundler/ruby_version"
-  autoload :Runtime,                "bundler/runtime"
-  autoload :Settings,               "bundler/settings"
-  autoload :SharedHelpers,          "bundler/shared_helpers"
-  autoload :Source,                 "bundler/source"
-  autoload :SourceList,             "bundler/source_list"
-  autoload :SpecSet,                "bundler/spec_set"
-  autoload :StubSpecification,      "bundler/stub_specification"
-  autoload :UI,                     "bundler/ui"
-  autoload :URICredentialsFilter,   "bundler/uri_credentials_filter"
-  autoload :VersionRanges,          "bundler/version_ranges"
+  autoload :Definition,             File.expand_path("bundler/definition", __dir__)
+  autoload :Dependency,             File.expand_path("bundler/dependency", __dir__)
+  autoload :DepProxy,               File.expand_path("bundler/dep_proxy", __dir__)
+  autoload :Deprecate,              File.expand_path("bundler/deprecate", __dir__)
+  autoload :Dsl,                    File.expand_path("bundler/dsl", __dir__)
+  autoload :EndpointSpecification,  File.expand_path("bundler/endpoint_specification", __dir__)
+  autoload :Env,                    File.expand_path("bundler/env", __dir__)
+  autoload :Fetcher,                File.expand_path("bundler/fetcher", __dir__)
+  autoload :FeatureFlag,            File.expand_path("bundler/feature_flag", __dir__)
+  autoload :GemHelper,              File.expand_path("bundler/gem_helper", __dir__)
+  autoload :GemHelpers,             File.expand_path("bundler/gem_helpers", __dir__)
+  autoload :GemRemoteFetcher,       File.expand_path("bundler/gem_remote_fetcher", __dir__)
+  autoload :GemVersionPromoter,     File.expand_path("bundler/gem_version_promoter", __dir__)
+  autoload :Graph,                  File.expand_path("bundler/graph", __dir__)
+  autoload :Index,                  File.expand_path("bundler/index", __dir__)
+  autoload :Injector,               File.expand_path("bundler/injector", __dir__)
+  autoload :Installer,              File.expand_path("bundler/installer", __dir__)
+  autoload :LazySpecification,      File.expand_path("bundler/lazy_specification", __dir__)
+  autoload :LockfileParser,         File.expand_path("bundler/lockfile_parser", __dir__)
+  autoload :MatchPlatform,          File.expand_path("bundler/match_platform", __dir__)
+  autoload :ProcessLock,            File.expand_path("bundler/process_lock", __dir__)
+  autoload :RemoteSpecification,    File.expand_path("bundler/remote_specification", __dir__)
+  autoload :Resolver,               File.expand_path("bundler/resolver", __dir__)
+  autoload :Retry,                  File.expand_path("bundler/retry", __dir__)
+  autoload :RubyDsl,                File.expand_path("bundler/ruby_dsl", __dir__)
+  autoload :RubyGemsGemInstaller,   File.expand_path("bundler/rubygems_gem_installer", __dir__)
+  autoload :RubyVersion,            File.expand_path("bundler/ruby_version", __dir__)
+  autoload :Runtime,                File.expand_path("bundler/runtime", __dir__)
+  autoload :Settings,               File.expand_path("bundler/settings", __dir__)
+  autoload :SharedHelpers,          File.expand_path("bundler/shared_helpers", __dir__)
+  autoload :Source,                 File.expand_path("bundler/source", __dir__)
+  autoload :SourceList,             File.expand_path("bundler/source_list", __dir__)
+  autoload :SpecSet,                File.expand_path("bundler/spec_set", __dir__)
+  autoload :StubSpecification,      File.expand_path("bundler/stub_specification", __dir__)
+  autoload :UI,                     File.expand_path("bundler/ui", __dir__)
+  autoload :URICredentialsFilter,   File.expand_path("bundler/uri_credentials_filter", __dir__)
+  autoload :VersionRanges,          File.expand_path("bundler/version_ranges", __dir__)
 
   class << self
     def configure
diff --git a/lib/bundler/fetcher.rb b/lib/bundler/fetcher.rb
index 7ec41d62c0..d21baf659d 100644
--- a/lib/bundler/fetcher.rb
+++ b/lib/bundler/fetcher.rb
@@ -9,10 +9,10 @@ require "rubygems/request"
 module Bundler
   # Handles all the fetching with the rubygems server
   class Fetcher
-    autoload :CompactIndex, "bundler/fetcher/compact_index"
-    autoload :Downloader, "bundler/fetcher/downloader"
-    autoload :Dependency, "bundler/fetcher/dependency"
-    autoload :Index, "bundler/fetcher/index"
+    autoload :CompactIndex, File.expand_path("fetcher/compact_index", __dir__)
+    autoload :Downloader, File.expand_path("fetcher/downloader", __dir__)
+    autoload :Dependency, File.expand_path("fetcher/dependency", __dir__)
+    autoload :Index, File.expand_path("fetcher/index", __dir__)
 
     # This error is raised when it looks like the network is down
     class NetworkDownError < HTTPError; end
diff --git a/lib/bundler/fetcher/compact_index.rb b/lib/bundler/fetcher/compact_index.rb
index 1efd3e03af..f36d76d4ae 100644
--- a/lib/bundler/fetcher/compact_index.rb
+++ b/lib/bundler/fetcher/compact_index.rb
@@ -4,7 +4,7 @@ require_relative "base"
 require_relative "../worker"
 
 module Bundler
-  autoload :CompactIndexClient, "bundler/compact_index_client"
+  autoload :CompactIndexClient, File.expand_path("../compact_index_client", __dir__)
 
   class Fetcher
     class CompactIndex < Base
diff --git a/lib/bundler/plugin/api.rb b/lib/bundler/plugin/api.rb
index a2d5cbb4ac..ee2bffe3ab 100644
--- a/lib/bundler/plugin/api.rb
+++ b/lib/bundler/plugin/api.rb
@@ -23,7 +23,7 @@ module Bundler
   # and hooks).
   module Plugin
     class API
-      autoload :Source, "bundler/plugin/api/source"
+      autoload :Source, File.expand_path("api/source", __dir__)
 
       # The plugins should declare that they handle a command through this helper.
       #
diff --git a/lib/bundler/plugin/installer.rb b/lib/bundler/plugin/installer.rb
index 4a262efac2..bcea3f0e45 100644
--- a/lib/bundler/plugin/installer.rb
+++ b/lib/bundler/plugin/installer.rb
@@ -8,8 +8,8 @@ module Bundler
   # are heavily dependent on the Gemfile.
   module Plugin
     class Installer
-      autoload :Rubygems, "bundler/plugin/installer/rubygems"
-      autoload :Git,      "bundler/plugin/installer/git"
+      autoload :Rubygems, File.expand_path("installer/rubygems", __dir__)
+      autoload :Git,      File.expand_path("installer/git", __dir__)
 
       def install(names, options)
         check_sources_consistency!(options)
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index 6cc25bc998..6d63745ae6 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -4,9 +4,9 @@ require "uri"
 
 module Bundler
   class Settings
-    autoload :Mirror,  "bundler/mirror"
-    autoload :Mirrors, "bundler/mirror"
-    autoload :Validator, "bundler/settings/validator"
+    autoload :Mirror,  File.expand_path("mirror", __dir__)
+    autoload :Mirrors, File.expand_path("mirror", __dir__)
+    autoload :Validator, File.expand_path("settings/validator", __dir__)
 
     BOOL_KEYS = %w[
       allow_bundler_dependency_conflicts
diff --git a/lib/bundler/shared_helpers.rb b/lib/bundler/shared_helpers.rb
index e56a44a559..da2a384d29 100644
--- a/lib/bundler/shared_helpers.rb
+++ b/lib/bundler/shared_helpers.rb
@@ -291,8 +291,9 @@ module Bundler
 
     def set_rubyopt
       rubyopt = [ENV["RUBYOPT"]].compact
-      return if !rubyopt.empty? && rubyopt.first =~ %r{-rbundler/setup}
-      rubyopt.unshift %(-rbundler/setup)
+      setup_require = "-r#{File.expand_path("setup", __dir__)}"
+      return if !rubyopt.empty? && rubyopt.first =~ /#{setup_require}/
+      rubyopt.unshift %(#{setup_require})
       Bundler::SharedHelpers.set_env "RUBYOPT", rubyopt.join(" ")
     end
 
diff --git a/lib/bundler/source.rb b/lib/bundler/source.rb
index 26a3625bb1..4b2e305bda 100644
--- a/lib/bundler/source.rb
+++ b/lib/bundler/source.rb
@@ -2,11 +2,11 @@
 
 module Bundler
   class Source
-    autoload :Gemspec,  "bundler/source/gemspec"
-    autoload :Git,      "bundler/source/git"
-    autoload :Metadata, "bundler/source/metadata"
-    autoload :Path,     "bundler/source/path"
-    autoload :Rubygems, "bundler/source/rubygems"
+    autoload :Gemspec,  File.expand_path("source/gemspec", __dir__)
+    autoload :Git,      File.expand_path("source/git", __dir__)
+    autoload :Metadata, File.expand_path("source/metadata", __dir__)
+    autoload :Path,     File.expand_path("source/path", __dir__)
+    autoload :Rubygems, File.expand_path("source/rubygems", __dir__)
 
     attr_accessor :dependency_names
 
diff --git a/lib/bundler/source/git.rb b/lib/bundler/source/git.rb
index aa24a87ed7..ed16f4a4e0 100644
--- a/lib/bundler/source/git.rb
+++ b/lib/bundler/source/git.rb
@@ -6,7 +6,7 @@ require "uri"
 module Bundler
   class Source
     class Git < Path
-      autoload :GitProxy, "bundler/source/git/git_proxy"
+      autoload :GitProxy, File.expand_path("git/git_proxy", __dir__)
 
       attr_reader :uri, :ref, :branch, :options, :submodules
 
diff --git a/lib/bundler/source/path.rb b/lib/bundler/source/path.rb
index 5f3f1bc2e4..c1d25fc4da 100644
--- a/lib/bundler/source/path.rb
+++ b/lib/bundler/source/path.rb
@@ -3,7 +3,7 @@
 module Bundler
   class Source
     class Path < Source
-      autoload :Installer, "bundler/source/path/installer"
+      autoload :Installer, File.expand_path("path/installer", __dir__)
 
       attr_reader :path, :options, :root_path, :original_path
       attr_writer :name
diff --git a/lib/bundler/source/rubygems.rb b/lib/bundler/source/rubygems.rb
index 86fd329089..103faa6b80 100644
--- a/lib/bundler/source/rubygems.rb
+++ b/lib/bundler/source/rubygems.rb
@@ -6,7 +6,7 @@ require "rubygems/user_interaction"
 module Bundler
   class Source
     class Rubygems < Source
-      autoload :Remote, "bundler/source/rubygems/remote"
+      autoload :Remote, File.expand_path("rubygems/remote", __dir__)
 
       # Use the API when installing less than X gems
       API_REQUEST_LIMIT = 500
diff --git a/lib/bundler/ui.rb b/lib/bundler/ui.rb
index 8138b30d38..7a4fa03669 100644
--- a/lib/bundler/ui.rb
+++ b/lib/bundler/ui.rb
@@ -2,8 +2,8 @@
 
 module Bundler
   module UI
-    autoload :RGProxy, "bundler/ui/rg_proxy"
-    autoload :Shell,   "bundler/ui/shell"
-    autoload :Silent,  "bundler/ui/silent"
+    autoload :RGProxy, File.expand_path("ui/rg_proxy", __dir__)
+    autoload :Shell,   File.expand_path("ui/shell", __dir__)
+    autoload :Silent,  File.expand_path("ui/silent", __dir__)
   end
 end
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo.rb b/lib/bundler/vendor/molinillo/lib/molinillo.rb
index 9e2867144f..baedefe98b 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo.rb
@@ -1,11 +1,11 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/compatibility'
-require 'bundler/vendor/molinillo/lib/molinillo/gem_metadata'
-require 'bundler/vendor/molinillo/lib/molinillo/errors'
-require 'bundler/vendor/molinillo/lib/molinillo/resolver'
-require 'bundler/vendor/molinillo/lib/molinillo/modules/ui'
-require 'bundler/vendor/molinillo/lib/molinillo/modules/specification_provider'
+require_relative 'molinillo/compatibility'
+require_relative 'molinillo/gem_metadata'
+require_relative 'molinillo/errors'
+require_relative 'molinillo/resolver'
+require_relative 'molinillo/modules/ui'
+require_relative 'molinillo/modules/specification_provider'
 
 # Bundler::Molinillo is a generic dependency resolution algorithm.
 module Bundler::Molinillo
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb
index 677a8bd916..31578bb5bf 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph.rb
@@ -3,8 +3,8 @@
 require 'set'
 require 'tsort'
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/log'
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/vertex'
+require_relative 'dependency_graph/log'
+require_relative 'dependency_graph/vertex'
 
 module Bundler::Molinillo
   # A directed acyclic graph that is tuned to hold named dependencies
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_edge_no_circular.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_edge_no_circular.rb
index 9849aea2fe..946a08236e 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_edge_no_circular.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_edge_no_circular.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/action'
+require_relative 'action'
 module Bundler::Molinillo
   class DependencyGraph
     # @!visibility private
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_vertex.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_vertex.rb
index 0a1e08255b..483527daf8 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_vertex.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_vertex.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/action'
+require_relative 'action'
 module Bundler::Molinillo
   class DependencyGraph
     # @!visibility private
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/delete_edge.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/delete_edge.rb
index 1d9f4b327d..d81940585a 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/delete_edge.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/delete_edge.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/action'
+require_relative 'action'
 module Bundler::Molinillo
   class DependencyGraph
     # @!visibility private
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/detach_vertex_named.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/detach_vertex_named.rb
index 385dcbdd06..36fce7c526 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/detach_vertex_named.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/detach_vertex_named.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/action'
+require_relative 'action'
 module Bundler::Molinillo
   class DependencyGraph
     # @!visibility private
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/log.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/log.rb
index 8582dd19c1..6f0de19886 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/log.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/log.rb
@@ -1,11 +1,11 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_edge_no_circular'
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/add_vertex'
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/delete_edge'
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/detach_vertex_named'
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/set_payload'
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/tag'
+require_relative 'add_edge_no_circular'
+require_relative 'add_vertex'
+require_relative 'delete_edge'
+require_relative 'detach_vertex_named'
+require_relative 'set_payload'
+require_relative 'tag'
 
 module Bundler::Molinillo
   class DependencyGraph
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/set_payload.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/set_payload.rb
index 37286d104a..2e9b90e6cd 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/set_payload.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/set_payload.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/action'
+require_relative 'action'
 module Bundler::Molinillo
   class DependencyGraph
     # @!visibility private
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/tag.rb b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/tag.rb
index d6ad16e07a..fccfc78cc7 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/tag.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/dependency_graph/tag.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph/action'
+require_relative 'action'
 module Bundler::Molinillo
   class DependencyGraph
     # @!visibility private
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/errors.rb b/lib/bundler/vendor/molinillo/lib/molinillo/errors.rb
index ce0931f103..89c7c324d5 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/errors.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/errors.rb
@@ -80,7 +80,7 @@ module Bundler::Molinillo
       @specification_provider = specification_provider
     end
 
-    require 'bundler/vendor/molinillo/lib/molinillo/delegates/specification_provider'
+    require_relative 'delegates/specification_provider'
     include Delegates::SpecificationProvider
 
     # @return [String] An error message that includes requirement trees,
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb b/lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb
index 0eb665d17a..acf7777414 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/resolution.rb
@@ -238,11 +238,11 @@ module Bundler::Molinillo
         debug { 'Activated: ' + Hash[activated.vertices.select { |_n, v| v.payload }].keys.join(', ') } if state
       end
 
-      require 'bundler/vendor/molinillo/lib/molinillo/state'
-      require 'bundler/vendor/molinillo/lib/molinillo/modules/specification_provider'
+      require_relative 'state'
+      require_relative 'modules/specification_provider'
 
-      require 'bundler/vendor/molinillo/lib/molinillo/delegates/resolution_state'
-      require 'bundler/vendor/molinillo/lib/molinillo/delegates/specification_provider'
+      require_relative 'delegates/resolution_state'
+      require_relative 'delegates/specification_provider'
 
       include Bundler::Molinillo::Delegates::ResolutionState
       include Bundler::Molinillo::Delegates::SpecificationProvider
diff --git a/lib/bundler/vendor/molinillo/lib/molinillo/resolver.rb b/lib/bundler/vendor/molinillo/lib/molinillo/resolver.rb
index 7d36858778..95eaab5991 100644
--- a/lib/bundler/vendor/molinillo/lib/molinillo/resolver.rb
+++ b/lib/bundler/vendor/molinillo/lib/molinillo/resolver.rb
@@ -1,6 +1,6 @@
 # frozen_string_literal: true
 
-require 'bundler/vendor/molinillo/lib/molinillo/dependency_graph'
+require_relative 'dependency_graph'
 
 module Bundler::Molinillo
   # This class encapsulates a dependency resolver.
@@ -9,7 +9,7 @@ module Bundler::Molinillo
   #
   #
   class Resolver
-    require 'bundler/vendor/molinillo/lib/molinillo/resolution'
+    require_relative 'resolution'
 
     # @return [SpecificationProvider] the specification provider used
     #   in the resolution process
diff --git a/lib/bundler/vendor/thor/lib/thor/base.rb b/lib/bundler/vendor/thor/lib/thor/base.rb
index e79d03d087..f55b14fbfc 100644
--- a/lib/bundler/vendor/thor/lib/thor/base.rb
+++ b/lib/bundler/vendor/thor/lib/thor/base.rb
@@ -9,9 +9,9 @@ require "bundler/vendor/thor/lib/thor/line_editor"
 require "bundler/vendor/thor/lib/thor/util"
 
 class Bundler::Thor
-  autoload :Actions,    "bundler/vendor/thor/lib/thor/actions"
-  autoload :RakeCompat, "bundler/vendor/thor/lib/thor/rake_compat"
-  autoload :Group,      "bundler/vendor/thor/lib/thor/group"
+  autoload :Actions,    File.expand_path("actions", __dir__)
+  autoload :RakeCompat, File.expand_path("rake_compat", __dir__)
+  autoload :Group,      File.expand_path("group", __dir__)
 
   # Shortcuts for help.
   HELP_MAPPINGS       = %w(-h -? --help -D)
diff --git a/lib/bundler/vendor/thor/lib/thor/shell.rb b/lib/bundler/vendor/thor/lib/thor/shell.rb
index a68cdf8a98..e36fa472d6 100644
--- a/lib/bundler/vendor/thor/lib/thor/shell.rb
+++ b/lib/bundler/vendor/thor/lib/thor/shell.rb
@@ -24,9 +24,9 @@ class Bundler::Thor
     SHELL_DELEGATED_METHODS = [:ask, :error, :set_color, :yes?, :no?, :say, :say_status, :print_in_columns, :print_table, :print_wrapped, :file_collision, :terminal_width]
     attr_writer :shell
 
-    autoload :Basic, "bundler/vendor/thor/lib/thor/shell/basic"
-    autoload :Color, "bundler/vendor/thor/lib/thor/shell/color"
-    autoload :HTML,  "bundler/vendor/thor/lib/thor/shell/html"
+    autoload :Basic, File.expand_path("shell/basic", __dir__)
+    autoload :Color, File.expand_path("shell/color", __dir__)
+    autoload :HTML,  File.expand_path("shell/html", __dir__)
 
     # Add shell to initialize config values.
     #
diff --git a/lib/bundler/version.rb b/lib/bundler/version.rb
index cfd6300950..21eeeb0fd4 100644
--- a/lib/bundler/version.rb
+++ b/lib/bundler/version.rb
@@ -1,23 +1,7 @@
 # frozen_string_literal: false
 
 module Bundler
-  # We're doing this because we might write tests that deal
-  # with other versions of bundler and we are unsure how to
-  # handle this better.
-  VERSION = "2.1.0.pre.1".freeze unless defined?(::Bundler::VERSION)
-
-  def self.overwrite_loaded_gem_version
-    begin
-      require "rubygems"
-    rescue LoadError
-      return
-    end
-    return unless bundler_spec = Gem.loaded_specs["bundler"]
-    return if bundler_spec.version == VERSION
-    bundler_spec.version = Bundler::VERSION
-  end
-  private_class_method :overwrite_loaded_gem_version
-  overwrite_loaded_gem_version
+  VERSION = "2.1.0.pre.1".freeze
 
   def self.bundler_major_version
     @bundler_major_version ||= VERSION.split(".").first.to_i
diff --git a/spec/bundler/shared_helpers_spec.rb b/spec/bundler/shared_helpers_spec.rb
index 7cd6aa7566..a9bf67b0d5 100644
--- a/spec/bundler/shared_helpers_spec.rb
+++ b/spec/bundler/shared_helpers_spec.rb
@@ -237,7 +237,7 @@ RSpec.describe Bundler::SharedHelpers do
     shared_examples_for "ENV['RUBYOPT'] gets set correctly" do
       it "ensures -rbundler/setup is at the beginning of ENV['RUBYOPT']" do
         subject.set_bundle_environment
-        expect(ENV["RUBYOPT"].split(" ")).to start_with("-rbundler/setup")
+        expect(ENV["RUBYOPT"].split(" ")).to start_with("-r#{File.expand_path("../../lib/bundler/setup", __dir__)}")
       end
     end
 
diff --git a/spec/commands/exec_spec.rb b/spec/commands/exec_spec.rb
index 39e27e94f2..8f49c576b5 100644
--- a/spec/commands/exec_spec.rb
+++ b/spec/commands/exec_spec.rb
@@ -279,7 +279,7 @@ RSpec.describe "bundle exec" do
     G
 
     rubyopt = ENV["RUBYOPT"]
-    rubyopt = "-rbundler/setup #{rubyopt}"
+    rubyopt = "-r#{File.expand_path("../../lib/bundler/setup", __dir__)} #{rubyopt}"
 
     bundle "exec 'echo $RUBYOPT'"
     expect(out).to have_rubyopts(rubyopt)
diff --git a/spec/support/hax.rb b/spec/support/hax.rb
index b14e4a5943..202e8dcc32 100644
--- a/spec/support/hax.rb
+++ b/spec/support/hax.rb
@@ -21,6 +21,8 @@ module Gem
 end
 
 if ENV["BUNDLER_SPEC_VERSION"]
+  require "bundler/version"
+
   module Bundler
     remove_const(:VERSION) if const_defined?(:VERSION)
     VERSION = ENV["BUNDLER_SPEC_VERSION"].dup