Fix failed merge when filename is the same as target branchname.

lib/gitlab/satellite/merge_action.rb

@@ -149,7 +149,7 @@ module Gitlab
           # We can't trust the input here being branch names, we can't always check it out because it could be a relative ref i.e. HEAD~3
           # we could actually remove the if true, because it should never ever happen (as long as the satellite has been prepared)
           repo.git.checkout(default_options, "#{merge_request.source_branch}")
-          repo.git.checkout(default_options, "#{merge_request.target_branch}")
+          repo.git.checkout(default_options({t: true}), "origin/#{merge_request.target_branch}")
         end
       rescue Grit::Git::CommandFailed => ex
         handle_exception(ex)