git new-branch displays an explanatory line.

git_new_branch.py

 #!/usr/bin/env python
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import argparse
 import sys
 
 import subprocess2
 
@@ skipping 23 matching lines @@
       if opts.upstream in tags():
         # TODO(iannucci): ensure that basis_ref is an ancestor of HEAD?
         run('checkout', '--no-track', '-b', opts.branch_name,
             hash_one(opts.upstream))
         set_config('branch.%s.remote' % opts.branch_name, '.')
         set_config('branch.%s.merge' % opts.branch_name, opts.upstream)
       else:
         # TODO(iannucci): Detect unclean workdir then stash+pop if we need to
         # teleport to a conflicting portion of history?
         run('checkout', '--track', opts.upstream, '-b', opts.branch_name)
-
     get_or_create_merge_base(opts.branch_name)
   except subprocess2.CalledProcessError as cpe:
     sys.stdout.write(cpe.stdout)
     sys.stderr.write(cpe.stderr)
     return 1
+  sys.stderr.write('Switched to branch %s.' % opts.branch_name)
 
 
 if __name__ == '__main__':  # pragma: no cover
   sys.exit(main(sys.argv[1:]))