hgext/narrow/narrowrepo.py

streamclone: avoid some obscure error in a corner case

I don't really know how, but I ran into this error:

    $ hg clone --stream ssh://user@dummy/empty-repo local-empty-repo
    streaming all changes
    abort: unable to apply stream clone: unsupported format:
    [255]

I think you need an empty list of requirements for this to happen,
which is weird, but an obscure error like this is not exactly helpful
either. Since this is the result of an encoding bug anyway, just fix
it.

Differential Revision: https://phab.mercurial-scm.org/D12402

# narrowrepo.py - repository which supports narrow revlogs, lazy loading
#
# Copyright 2017 Google, Inc.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

from mercurial import wireprototypes

from . import narrowdirstate


def wraprepo(repo):
    """Enables narrow clone functionality on a single local repository."""

    class narrowrepository(repo.__class__):
        def _makedirstate(self):
            dirstate = super(narrowrepository, self)._makedirstate()
            return narrowdirstate.wrapdirstate(self, dirstate)

        def peer(self):
            peer = super(narrowrepository, self).peer()
            peer._caps.add(wireprototypes.NARROWCAP)
            peer._caps.add(wireprototypes.ELLIPSESCAP)
            return peer

    repo.__class__ = narrowrepository