manifest: remove dependency on treeinmem from manifest.add
Currently manifest.add uses the treeinmem option to know if it can call
fastdelta on the given manifest instance. In a future patch we will be moving
add() to be on the manifestrevlog, so it won't have access to the treeinmem
option anymore. Instead, let's have it actually check if the given manifest
instance supports the fastdelta operation.
This also means that if treemanifest or any implementation eventually implements
fastdelta(), it will automatically benefit from this code path.
from __future__ import absolute_import
import pkgutil
__path__ = pkgutil.extend_path(__path__, __name__)