Fix gae.py's detection of current active credentials.

appengine/components/tools/gae.py

Index: appengine/components/tools/gae.py
diff --git a/appengine/components/tools/gae.py b/appengine/components/tools/gae.py
index ada7216a93bd22c10dcef79d22089c27c1d3096b..673adfcd7405d7f188fb456ef3f3d3e21e96a54b 100755
--- a/appengine/components/tools/gae.py
+++ b/appengine/components/tools/gae.py
@@ -72,6 +72,20 @@ def print_version_log(app, to_version):
 ##
 
 
+def CMDappcfg_login(parser, args):
+  """Sets up authentication for appcfg.py usage [DEPRECATED]."""
+  app, _, _ = parser.parse_args(args)
+  print (
+      'Since appcfg.py doesn\'t support explicit login command, we\'ll run '
+      'innocent "list_version" instead. It will trigger appcfg\'s login flow. '
+      '\n'
+      'It\'s fine if "list_version" call itself fails - at this point we have '
+      'the necessary credentials cached and other subcommands should be able '
+      'to use them.\n')
+  gae_sdk_utils.appcfg_login(app)
+  return 0
+
+
 def CMDactive(parser, args):
   """Prints the active versions on the server.