LOCALE_PATHS should have a check to make sure it's a list/tuple

[Tim Shaffer]

I'm playing around with 1.7b4 and I was trying to track down why my app was not auto-reloading when files were changed using the dev server.

Turns out, it was an improperly configured LOCALE_PATHS setting.

My LOCALE_PATHS was configured like this:

LOCALE_PATHS = (

    '/path/to/locale'

)

At first glance, it looks okay. But it's actually a string and not a tuple since it does not have a comma.

This causes a problem in the autoloader, here:

https://github.com/django/django/blob/608e6eb2959c6e56e5c702ca0d15fa0e6c2eef16/django/utils/autoreload.py#L98

This would be fine, but since LOCALE_PATHS is a string, calling basedirs.extend(LOCALE_PATHS) actually causes every character in the string to get appended to basedirs. Then it walks through the tree and tries to find .mo files. And since there are 3 slashes in the string, the autoloader attempts to search the root drive 3 times.

Bottom line is that having LOCALE_PATHS set to a string with slashes causes autoreloading to essentially take forever. 

Maybe adding a warning/validation to ensure LOCALE_PATHS is a list/tuple would be a good idea?

[Tim Graham]

Sure, patches welcome. `django.conf.__init__` already has some "tuple_settings" logic which is looks like would probably work for this.