Unable to reverse a run_before that refers to django.contrib.auth

[Matthew Schinckel]

You can use run_before to ensure that something else runs before django.contrib.auth (specifically ('auth', '0001_initial'), but if you try to reverse that migration, a signal fires that tries to update permissions.

Since this will run after auth_permission has been dropped, it will result in a database error.

[Matthew Schinckel]

I have a minimal example at ​https://bitbucket.org/schinckel/runs_before/src

Not sure how to write up a nice django test case for this though.

[Tim Graham]

#24075 describes a closely related problem caused by the fact that signal handlers run unconditionally. The solution started in ​PR #5835 might also fix this.

[Matthew Schinckel]

Yeah, the behaviour is the same as migrating auth to zero. I'd missed that (my test obviously didn't unmigrate that app, only the one I was testing, which when I put the run_before cascaded to migrating auth to zero).

[Simon Charette]

Closing as duplicate of #24075.