[rubygems/rubygems] Truly ignore commented out settings

https://github.com/rubygems/rubygems/commit/e31df2d6ef

lib/bundler/settings.rb

@@ -538,7 +538,7 @@ module Bundler
       key.gsub!("-", "___")
       key.upcase!
 
-      key.prepend("BUNDLE_")
+      key.gsub(/\A([ #]*)/, '\1BUNDLE_')
     end
 
     # TODO: duplicates Rubygems#normalize_uri

spec/bundler/commands/config_spec.rb

@@ -447,7 +447,7 @@ E
     it "does not make bundler crash and ignores the configuration" do
       bundle "config list --parseable"
 
-      expect(out).to eq("#mirror.https://rails-assets.org/=http://localhost:9292")
+      expect(out).to be_empty
       expect(err).to be_empty
 
       ruby(<<~RUBY)