Make switch command even more helpful with branch name

Author: Katrin Leinweber

gitless/cli/gl_switch.py

@@ -30,7 +30,7 @@ def main(args, repo):
   if not b:
     pprint.err('Branch {0} doesn\'t exist'.format(args.branch))
     pprint.err_exp('to list existing branches do gl branch')
-    pprint.err_exp('to create a new branch do gl branch -c feature/foo')
+    pprint.err_exp('to create a new branch do gl branch -c {0}'.format(args.branch))
     return False
 
   repo.switch_current_branch(b, move_over=args.move_over)