@tonglil Sounds good. I won't be able to merge or tag anything in this though

Thanks, @mattgrunwald I have tagged 0.3.0 release.

Hi @mattgrunwald, unfortunately due to incompatible changes being introduced with the sdk upgrade, we had to revert this PR.

Before upgrading the sdk any further, the plugin should be migrated off of using appcfg. I believe this is possible without introducing a breaking change as the drone plugin parameter interface can abstract the changes from the user.

The issue that was identified was this:

Running Command: /go_appengine/appcfg.py  --oauth2_access_token  [redacted] 

 -A redacted -V 64c97e9638b4e0c7939751ee26cef8c120f6643f update_dispatch .

/usr/bin/env: 'python': No such file or directory

error: exit status 127

I'm hesitant to introduce a potential stopgap of adding or configuring python because this simply propagates the usage of the no longer supported usage of appcfg (see here).

July 30, 2019

The AppCfg tooling and the legacy standalone App Engine SDK, delivered through the GoogleAppEngineLauncher.dmg, GoogleAppEngine.msi, and google_appengine.zip files, are now deprecated. Google will shut down and remove support on July 30, 2020.

The functionalities of the App Engine SDK is delivered exclusively through [Cloud SDK](https://cloud.google.com/sdk/docs). For more information, see [Migrating to Cloud SDK](https://cloud.google.com/appengine/docs/standard/java/sdk-gcloud-migration).