Auto merge of #5650 - bundler:seg-mirror-file-uri-case, r=indirect

[Mirror] Properly handle casing of file URIs

This came up when running the bundler specs in a path that had at least 1 upper case character

```
Run options:
  include {:last_run_status=>"failed"}
  exclude {:rubygems_master=>true, :git=>"=< 2.9.0", :rubygems=>"=< 2.6.12", :ruby=>"=< 2.3.1", :realworld=>true, :sudo=>true}
bundle install
  with bundler dependencies
$ /Users/kenrettberg/.rbenv/versions/2.3.1/bin/ruby -rubygems -S gem --backtrace generate_index
Generating Marshal quick index gemspecs for 64 gems
................................................................
Complete
Generated Marshal quick index gemspecs: 0.036s
Generating specs index
Generated specs index: 0.000s
Generating latest specs index
Generated latest specs index: 0.000s
Generating prerelease specs index
Generated prerelease specs index: 0.000s
Compressing indices
Compressed indices: 0.001s
# $? => 0
$ /Users/kenrettberg/.rbenv/versions/2.3.1/bin/ruby -I/Users/kenrettberg/opensource/bundler/lib:/Users/kenrettberg/opensource/bundler/spec -r/Users/kenrettberg/opensource/bundler/spec/support/artifice/fail.rb -rsupport/hax /Users/kenrettberg/opensource/bundler/exe/bundle install --retry 0 --no-color
Fetching source index from file:/users/kenrettberg/opensource/bundler/tmp/gems/remote2/
Resolving dependencies...
Bundler could not find compatible versions for gem "bundler":
  In Gemfile:
    bundler (= 0.9.2)
  Current Bundler version:
    bundler (1.15.0.pre.3)
This Gemfile requires a different version of Bundler.
Perhaps you need to update Bundler by running `gem install bundler`?
Could not find gem 'bundler (= 0.9.2)' in any of the sources
# $? => 6
    causes a conflict if explicitly requesting a different version (FAILED - 1)
Retried examples: 0
Failures:
  1) bundle install with bundler dependencies causes a conflict if explicitly requesting a different version
     Failure/Error: expect(out).to eq(nice_error)

       expected: "Fetching source index from file:/Users/kenrettberg/opensource/bundler/tmp/gems/remote2/\nResolving d...r by running `gem install bundler`?\n\nCould not find gem 'bundler (= 0.9.2)' in any of the sources"
            got: "Fetching source index from file:/users/kenrettberg/opensource/bundler/tmp/gems/remote2/\nResolving d...r by running `gem install bundler`?\n\nCould not find gem 'bundler (= 0.9.2)' in any of the sources"

       (compared using ==)

       Diff:
       @@ -1,4 +1,4 @@
       -Fetching source index from file:/Users/kenrettberg/opensource/bundler/tmp/gems/remote2/
       +Fetching source index from file:/users/kenrettberg/opensource/bundler/tmp/gems/remote2/
        Resolving dependencies...
        Bundler could not find compatible versions for gem "bundler":
          In Gemfile:

       Commands:
       $ /Users/kenrettberg/.rbenv/versions/2.3.1/bin/ruby -rubygems -S gem --backtrace generate_index
       Generating Marshal quick index gemspecs for 64 gems
       ................................................................
       Complete
       Generated Marshal quick index gemspecs: 0.036s
       Generating specs index
       Generated specs index: 0.000s
       Generating latest specs index
       Generated latest specs index: 0.000s
       Generating prerelease specs index
       Generated prerelease specs index: 0.000s
       Compressing indices
       Compressed indices: 0.001s
       # $? => 0

       $ /Users/kenrettberg/.rbenv/versions/2.3.1/bin/ruby -I/Users/kenrettberg/opensource/bundler/lib:/Users/kenrettberg/opensource/bundler/spec -r/Users/kenrettberg/opensource/bundler/spec/support/artifice/fail.rb -rsupport/hax /Users/kenrettberg/opensource/bundler/exe/bundle install --retry 0 --no-color
       Fetching source index from file:/users/kenrettberg/opensource/bundler/tmp/gems/remote2/
       Resolving dependencies...
       Bundler could not find compatible versions for gem "bundler":
         In Gemfile:
           bundler (= 0.9.2)

         Current Bundler version:
           bundler (1.15.0.pre.3)
       This Gemfile requires a different version of Bundler.
       Perhaps you need to update Bundler by running `gem install bundler`?

       Could not find gem 'bundler (= 0.9.2)' in any of the sources
       # $? => 6
     # ./spec/install/bundler_spec.rb:54:in `block (3 levels) in <top (required)>'
Finished in 2.4 seconds (files took 1.66 seconds to load)
1 example, 1 failure
Failed examples:
rspec ./spec/install/bundler_spec.rb:33 # bundle install with bundler dependencies causes a conflict if explicitly requesting a different version
```

Notice the failure is just in the casing of the path... but that path is actually a file URI that is printed by a `Mirror` instance. Tracing back that initialization led me to undoing some down casing, so hopefully this is more correct without introducing any further regressions?

3 files changed, 20 insertions, 3 deletions

diff --git a/lib/bundler/mirror.rb b/lib/bundler/mirror.rb
index 9903e158ab..8a081ba91f 100644
--- a/lib/bundler/mirror.rb
+++ b/lib/bundler/mirror.rb
@@ -45,7 +45,8 @@ module Bundler
     private
 
       def fetch_valid_mirror_for(uri)
-        mirror = @mirrors[uri.to_s.downcase] || @mirrors[URI(uri.to_s).host] || Mirror.new(uri)
+        downcased = uri.to_s.downcase
+        mirror = @mirrors[downcased] || @mirrors[URI(downcased).host] || Mirror.new(uri)
         mirror.validate!(@prober)
         mirror = Mirror.new(uri) unless mirror.valid?
         mirror
@@ -72,7 +73,7 @@ module Bundler
         @uri = if uri.nil?
           nil
         else
-          URI(uri.to_s.downcase)
+          URI(uri.to_s)
         end
         @valid = nil
       end
diff --git a/lib/bundler/settings.rb b/lib/bundler/settings.rb
index 81cbb3953c..62c21a2ecb 100644
--- a/lib/bundler/settings.rb
+++ b/lib/bundler/settings.rb
@@ -344,7 +344,7 @@ module Bundler
       unless uri.absolute?
         raise ArgumentError, format("Gem sources must be absolute. You provided '%s'.", uri)
       end
-      "#{prefix}#{uri}#{suffix}".downcase
+      "#{prefix}#{uri}#{suffix}"
     end
   end
 end
diff --git a/spec/bundler/settings_spec.rb b/spec/bundler/settings_spec.rb
index ec01827500..a93c41b7d2 100644
--- a/spec/bundler/settings_spec.rb
+++ b/spec/bundler/settings_spec.rb
@@ -184,6 +184,22 @@ that would suck --ehhh=oh geez it looks like i might have broken bundler somehow
       it "is case insensitive" do
         expect(settings.mirror_for("HTTPS://RUBYGEMS.ORG/")).to eq(mirror_uri)
       end
+
+      context "with a file URI" do
+        let(:mirror_uri) { URI("file:/foo/BAR/baz/qUx/") }
+
+        it "returns the mirror URI" do
+          expect(settings.mirror_for(uri)).to eq(mirror_uri)
+        end
+
+        it "converts a string parameter to a URI" do
+          expect(settings.mirror_for("file:/foo/BAR/baz/qUx/")).to eq(mirror_uri)
+        end
+
+        it "normalizes the URI" do
+          expect(settings.mirror_for("file:/foo/BAR/baz/qUx")).to eq(mirror_uri)
+        end
+      end
     end
   end