When I try to upload a sample csv data to my GAE app through appcfg.py, it shows the below 401 error.
2015-11-04 10:44:41,820 INFO client.py:571
I had a similar issue, where appcfg.py was not giving me any credentials dialog, so I could not authenticate. I downgraded from GAELauncher 1.27 to 1.26, and the authentication started working again.
Temporary solution: go to https://console.developers.google.com/storage/browser/appengine-sdks/featured/ to get version 1.9.26
Submitted bug report: https://code.google.com/p/google-cloud-sdk/issues/detail?id=340