BUG: 14824. Fix GetReaders().

Fixed logic in GetReaders when the filename is empty. The method is
supposed to return all possible readers, but due to a copy-paste error
it just returned an empty list.

Change-Id: Ida60f513ed152c8b6e9d1e3544d2503c60ec8b1f
Merge topic '14824_fix_reader_factory' into next

a10e3081 BUG: 14824. Fix GetReaders().