Merge branch 'sg/completion-omit-credential-helpers'

The Git subcommand completion (in contrib/) listed credential
helpers among candidates, which is not something the end user would
invoke interatively.

* sg/completion-omit-credential-helpers:
  completion: remove credential helpers from porcelain commands

contrib/completion/git-completion.bash

@@ -665,8 +665,8 @@ __git_list_porcelain_commands ()
 		checkout-index)   : plumbing;;
 		commit-tree)      : plumbing;;
 		count-objects)    : infrequent;;
-		credential-cache) : credentials helper;;
-		credential-store) : credentials helper;;
+		credential)       : credentials;;
+		credential-*)     : credentials helper;;
 		cvsexportcommit)  : export;;
 		cvsimport)        : import;;
 		cvsserver)        : daemon;;