[rubygems/rubygems] Save array allocation for every dependency in Gemfile

Only need to check for lack of git key when branch option is present

https://github.com/rubygems/rubygems/commit/ebfca1b389

lib/bundler/dsl.rb

@@ -404,13 +404,11 @@ module Bundler
     end
 
     def validate_keys(command, opts, valid_keys)
-      invalid_keys = opts.keys - valid_keys
-
-      git_source = opts.keys & @git_sources.keys.map(&:to_s)
-      if opts["branch"] && !(opts["git"] || opts["github"] || git_source.any?)
+      if opts["branch"] && !(opts["git"] || opts["github"] || (opts.keys & @git_sources.keys.map(&:to_s)).any?)
         raise GemfileError, %(The `branch` option for `#{command}` is not allowed. Only gems with a git source can specify a branch)
       end
 
+      invalid_keys = opts.keys - valid_keys
       return true unless invalid_keys.any?
 
       message = String.new