Assigning project roles intermittently throws PermissionSet.DoesNotExist

[oliverroick]

Steps to reproduce the error

This bug is difficult to reproduce. It happens sometimes when you try to assign new project roles to a user. On occasion PermissionSet.DoesNotExist is thrown. I have not yet been able to reproduce the pre-conditions under which the exception is thrown; this needs further investigation. Here's an example log from Opbeat: https://opbeat.com/cadasta/platform-demo/errors/79/

Actual behavior

An exception is thrown in some cases.

Expected behavior

The roles should be assigned without an exception.

[oliverroick]

Closing this as we're moving away from tutelary