largefiles: fix support for local largefiles while using share extension
Prior to revision
2a3f24786d09, largefiles were saved in the local repository,
even if it was using the share extension. After that change, all largefiles are
now stored in the shared repository. However, the backward compatibility for
existing largefiles already placed in the local repository was never tested,
and has been broken since.
http://example.com/no/anchor, branches: (None, [])
http://example.com/an/anchor, branches: ('foo', [])
http://example.com/no/anchor/branches, branches: (None, ['foo'])
http://example.com/an/anchor/branches, branches: ('bar', ['foo'])
http://example.com/an/anchor/branches-None, branches: ('foo', [])
http://example.com/, branches: (None, [])
http://example.com/, branches: (None, [])
http://example.com/, branches: ('foo', [])