Provide a fallback for pwd

[damien_szczyt]

I've created a UNIX user in a mysql database, but my settings doesn't allow the user to know its username via getpwuid.
This is a small patch to set the default username as 'admin' if getpwuid fails.

[Marc Fargas]

Altought I don't see why would one prevent getpwuid to work, why don't you first try to read the $USER variable?
That would be a better fallback, even:

default_username = os.environ.get('USER', 'admin')

would do the job.

Anyway, this has been deprecated, you should patch django/contrib/auth/management/commands/createsuperuser.py now.

[Malcolm Tredinnick]

Regarding this patch:

1. Bare excepts are bad. We should catch the right exception type explicitly.
2. If retrieving the default user doesn't work, it should be set to the empty string, just like if the pwd module cannot be imported. No reason to introduce any other default.
3. As telenieko mentioned, when the patch is updated to accommodate these changes, the relevant code is now in django/contrib/auth/management/commands/createsuperuser.py

[Jannis Leidel]

(In [14607]) Fixed #7077 and #7431 -- Use getpass.getuser instead of pwd.getpwuid to determine the current system user's username in the createsuperuser management command to enable the feature on Windows. getpass.getuser automatically falls back to the previous method.

[Jannis Leidel]

(In [14608]) [1.2.X] Fixed #7077 and #7431 -- Use getpass.getuser instead of pwd.getpwuid to determine the current system user's username in the createsuperuser management command to enable the feature on Windows. getpass.getuser automatically falls back to the previous method.

Backport from trunk (r14607).