id	summary	reporter	owner	description	type	status	component	version	severity	resolution	keywords	cc	stage	has_patch	needs_docs	needs_tests	needs_better_patch	easy	ui_ux
19822	USERNAME_FIELD should be validated as unique=True	Russell Keith-Magee	nobody	"The docs describe the fact that USERNAME_FIELD on a custom User model must be unique. Lots of code (e.g., login forms) work on the assumption that USERNAME_FIELD is unique. 

However, nothing actually enforces this requirement.

There should be a validation step to enforce the uniqueness of USERNAME_FIELD. It would also be advisable to enforce db_index=True (since username will be a common lookup field)

Marking as release blocker because it's an easy mistake for end-developers to make, and will cause all sorts of weird bugs if it isn't caught."	Cleanup/optimization	closed	contrib.auth	1.5-rc-1	Release blocker	fixed		chris.jerdonek@…	Accepted	1	0	0	0	0	0