AttributeError with custom routers that define allow_syncdb but not allow_migrate

[Neal Todd]

router.allow_syncdb is deprecated and will be removed in 1.9. However, although django.db.utils.ConnectionRouter.allow_migrate() issues a warning to that effect if allow_migrate is not defined, a subsequent line inspects the arguments for router.allow_migrate causing an AttributeError.

The attached patch inspects method set in the try-except block which will be whichever of allow_syncdb or allow_migrate is defined.

If it was allow_syncdb that was defined then the code will then go on to issue the warning about the signature change to allow_migrate (allow_syncdb has the same signature as the old allow_migrate signature). Given that this warning was preceded by the warning to rename the allow_syncdb method that shouldn't cause confusion.

[Tim Graham <timograham@…>]

In b81ce2e:

[1.8.x] Fixed #24532 -- Restored fallback support for allow_syncdb.