Removed unique=True from UserOpenID.claimed_id

[symbolist]

https://openedx.atlassian.net/browse/TNL-3664

django-openid-auth has claimed_id = TextField(unique=True). However, TextFields cannot be unique in MySQL: django/django@e8cbc2b
https://docs.djangoproject.com/en/1.8/ref/models/fields/#textfield
https://code.djangoproject.com/ticket/2495

This results in the following error when running migrations:
"django.db.utils.OperationalError: (1170, "BLOB/TEXT column 'claimed_id' used in key specification without a key length")"

[symbolist]

@macdiesel @nedbat I have imported the code from https://code.launchpad.net/django-openid-auth and made this change. Thoughts?

[symbolist]

Btw, it does fix the issue. And as far as I understand in Django 1.4 unique=True on TextFields was ignored. For example on a sandbox with Django 1.4 I do not see a unique index on this field.

[macdiesel]

👍

[symbolist]

@nedbat @doctoryes This needs one more review.

[doctoryes]

@symbolist Above, you say you "imported the code from launchpad and made this change." Does this mean you submitted the change upstream to the module itself? Other than this question, looks fine.

[symbolist]

@doctoryes We are planning to change the field to CharField later so this is not done yet. Also this makes a change to an existing migration. I am not sure if upstream can accept it.

[doctoryes]

👍

[doctoryes]

Shouldn't this PR be against the 'master' branch instead of the 'upstream' branch? Typically, an 'upstream' branch would reflect the state of the upstream repo - while 'master' would reflect our edX changes.

[doctoryes]

I'm going to hold off on merging this until @symbolist comments.

[symbolist]

@doctoryes When I was working on this, master did not have the right commit history, so I pushed the upstream code into the upstream branch. That has been resolved (master has the correct history) so we can merge these changes into master instead.