_make_token_with_timestamp inconsistent based on User.last_login

[felix]

default token generator makes inconsistent tokens depending on if the user has been loaded from the db or has just been created during this response

the difference is that a User just created has a last_login with microseconds set, but when reloaded from the db it does not and the token generator uses unicode(user.last_login) in the hash

from django.contrib.auth.models import User
u1 = User.objects.create_user("username","user@…","password")
u1.last_login

datetime.datetime(2009, 2, 14, 16, 5, 3, 638275)

unicode(u1.last_login)

u'2009-02-14 16:05:03.638275'

u2 = User.objects.all()[0]
u2

<User: crucial>

u2.last_login

datetime.datetime(2009, 2, 14, 15, 47, 20)

unicode(u2.last_login)

u'2009-02-14 15:47:20'

(as an aside, I don't think that a user should be created with a last login of now.
a new user has never logged in.)

# user just made, generate token:
making token 3 2009-02-14 16:24:33.632380 2966
2ae-c3c68b86d5148e768353

# user comes to site, token fails equality test in check_token
making token 3 2009-02-14 16:24:33 2966
2ae-e8d746b5603f6fae0fd5

the fix is to explicitly format user.last_login without microsecond

this fix should not break any currently generated tokens out there in email land