Remove persistent_gems_after_clean workaround

bundler/helpers/v1/lib/functions/lockfile_updater.rb

@@ -64,7 +64,7 @@ def cache_vendored_gems(definition)
       # Dependencies that have been unlocked for the update (including
       # sub-dependencies)
       unlocked_gems = definition.instance_variable_get(:@unlock).
-                      fetch(:gems).reject { |gem| __keep_on_prune?(gem) }
+                      fetch(:gems)
       bundler_opts = {
         cache_all: true,
         cache_all_platforms: true,
@@ -84,15 +84,6 @@ def cache_vendored_gems(definition)
       end
     end
 
-    # This is not officially supported and may be removed without notice.
-    def __keep_on_prune?(spec_name)
-      unless (specs = Bundler.settings[:persistent_gems_after_clean])
-        return false
-      end
-
-      specs.include?(spec_name)
-    end
-
     # Copied from Bundler::Runtime: Modified to only prune gems that have
     # been unlocked
     def prune_gem_cache(resolve, cache_path, unlocked_gems)

bundler/helpers/v2/lib/functions/lockfile_updater.rb

@@ -65,7 +65,7 @@ def cache_vendored_gems(definition)
       # Dependencies that have been unlocked for the update (including
       # sub-dependencies)
       unlocked_gems = definition.instance_variable_get(:@unlock).
-                      fetch(:gems).reject { |gem| __keep_on_prune?(gem) }
+                      fetch(:gems)
       bundler_opts = {
         cache_all: true,
         cache_all_platforms: true,
@@ -85,15 +85,6 @@ def cache_vendored_gems(definition)
       end
     end
 
-    # This is not officially supported and may be removed without notice.
-    def __keep_on_prune?(spec_name)
-      unless (specs = Bundler.settings[:persistent_gems_after_clean])
-        return false
-      end
-
-      specs.include?(spec_name)
-    end
-
     # Copied from Bundler::Runtime: Modified to only prune gems that have
     # been unlocked
     def prune_gem_cache(resolve, cache_path, unlocked_gems)

bundler/spec/dependabot/bundler/file_updater_spec.rb

@@ -1495,22 +1495,6 @@
         expect(file.operation).to eq Dependabot::DependencyFile::Operation::DELETE
       end
 
-      context "persistent gems after clean" do
-        let(:project_name) { "vendored_persistent_gems" }
-
-        it "does not delete cached files marked as persistent" do
-          file = updater.updated_dependency_files.find do |f|
-            f.name == "vendor/cache/business-1.4.0.gem"
-          end
-
-          vendor_files =
-            Dir.entries(Pathname.new(repo_contents_path).join("vendor/cache"))
-
-          expect(file).to be_nil
-          expect(vendor_files).to include("business-1.4.0.gem")
-        end
-      end
-
       context "with dependencies that are not unlocked by the update" do
         let(:project_name) { "conditional" }