Fixed #21014 -- Fixed gobbled ImportError in MigrationLoader.
Fixed #21015 -- Fixed MigrationLoader when importlib.import_module returns a file module or an empty directory.
Fixed #16096 -- Added origin attribute to template instances.

Thanks jdunck for the suggestion.
Fixed #20977 -- Fixed writing migrations to disk on Python 3
Merge branch 'master' of github.com:django/django into pscyopg_unicode