As @snakecharmerb observed the django packages are missing in the app-engine-python
component (1.9.49) of the cloud SDK (138.0.0).
They are, however, present in the standalone GAE SDK (also 1.9.49):
/usr/local # diff google_appengine_1.9.49/lib google-cloud-sdk-138.0.0/platform/google_appengine/lib | grep -vi common
Only in google_appengine_1.9.49/lib: django-0.96
Only in google_appengine_1.9.49/lib: django-1.2
Only in google_appengine_1.9.49/lib: django-1.3
Only in google_appengine_1.9.49/lib: django-1.4
Only in google_appengine_1.9.49/lib: django-1.5
Only in google_appengine_1.9.49/lib: django-1.9
Only in google_appengine_1.9.49/lib: graphy
So an alternative to vendoring django into your app might be to switch to this SDK instead of the cloud SDK. See What is the relationship between Google's App Engine SDK and Cloud SDK?, including comments.
Note that it's not the recommended way these days, tho.
You could also install both and try to copy/symlink the missing packages into the cloud SDK. YMMV.
To download the GAE SDK in the Download the SDK for App Engine page click on the Optionally, you can also download the original App Engine SDK for Python. "link" - it's actually a control for the expandable download section below:
