[rubygems/rubygems] Fix git source unlocking for multi-gem repositories like Rails

If you have

```
gem "rails", git: "https://github.com/rails/rails"
```

and then explicitly pin to an older ref, like

```
gem "rails", git: "https://github.com/rails/rails", ref: "https://github.com/rubygems/rubygems/commit/99bacb5aa8e5"
```

Then `bundle install` fails, because locked sources fail to be updated
to use the new source.

This commit fixes the problem by making sure get their source properly
replaced.

https://github.com/rubygems/rubygems/commit/5de8c2e0cf

lib/bundler/definition.rb

@@ -1045,7 +1045,7 @@ module Bundler
           s.source = gemfile_source
         else
           # Replace the locked dependency's source with the default source, if the locked source is no longer in the Gemfile
-          s.source = default_source unless sources.get(lockfile_source)
+          s.source = sources.get(lockfile_source) || default_source
         end
 
         source = s.source

lib/bundler/source_list.rb

@@ -103,7 +103,7 @@ module Bundler
     end
 
     def get(source)
-      source_list_for(source).find {|s| equivalent_source?(source, s) }
+      source_list_for(source).find {|s| s.include?(source) }
     end
 
     def lock_sources
@@ -265,9 +265,5 @@ module Bundler
     def equivalent_sources?(lock_sources, replacement_sources)
       lock_sources.sort_by(&:identifier) == replacement_sources.sort_by(&:identifier)
     end
-
-    def equivalent_source?(source, other_source)
-      source == other_source
-    end
   end
 end

spec/bundler/install/gemfile/git_spec.rb

@@ -1151,6 +1151,30 @@ RSpec.describe "bundle install with git sources" do
 
       expect(the_bundle).to include_gem "rails 7.1.4", "activesupport 7.1.4"
     end
+
+    it "doesn't explode when adding an explicit ref to a git gem with dependencies" do
+      lib_root = lib_path("rails")
+
+      build_lib "activesupport", "7.1.4", path: lib_root.join("activesupport")
+      build_git "rails", "7.1.4", path: lib_root do |s|
+        s.add_dependency "activesupport", "= 7.1.4"
+      end
+
+      old_revision = revision_for(lib_root)
+      update_git "rails", "7.1.4", path: lib_root
+
+      install_gemfile <<-G
+        source "https://gem.repo1"
+        gem "rails", "7.1.4", :git => "#{lib_root}"
+      G
+
+      install_gemfile <<-G
+        source "https://gem.repo1"
+        gem "rails", :git => "#{lib_root}", :ref => "#{old_revision}"
+      G
+
+      expect(the_bundle).to include_gem "rails 7.1.4", "activesupport 7.1.4"
+    end
   end
 
   describe "bundle install after the remote has been updated" do