Deprecate `bundle install --force`

Instead of hard erroring, deprecate the `--force` flag on bundler 2 to
better teach users about the replacement.

Before:

$ bundle install --force
Unknown switches '--force'

After:

$ bundle install --force
[DEPRECATED FOR 2.0] The `--force` option has been renamed to `--redownload`
Could not locate Gemfile # or whatever the expected behavior for --redownload is

1 files changed, 10 insertions, 0 deletions

diff --git a/spec/install/redownload_spec.rb b/spec/install/redownload_spec.rb
index 626a4a8e9f..d6fcc9c2b8 100644
--- a/spec/install/redownload_spec.rb
+++ b/spec/install/redownload_spec.rb
@@ -60,11 +60,21 @@ RSpec.describe "bundle install" do
     it_behaves_like "an option to force redownloading gems" do
       let(:flag) { "force" }
     end
+
+    it "shows a deprecation" do
+      bundle! :install, :force => true
+      expect(out).to include "[DEPRECATED FOR 2.0] The `--force` option has been renamed to `--redownload`"
+    end
   end
 
   describe "with --redownload" do
     it_behaves_like "an option to force redownloading gems" do
       let(:flag) { "redownload" }
     end
+
+    it "does not show a deprecation" do
+      bundle! :install, :redownload => true
+      expect(out).not_to include "[DEPRECATED FOR 2.0] The `--force` option has been renamed to `--redownload`"
+    end
   end
 end