debugcommands: prevent using `is False`
I was touching this code in a future patch and marmoute warned about usage of
`is False` here.
Quoting marmoute:
```
"is False" is going to check if the object you have the very same object in
memory than the one Python allocated for False (in practice 0)
This will "mostly work" on cpython because of implementation details, but
is semantically wrong and can start breaking unexpectedly
```
Differential Revision: https://phab.mercurial-scm.org/D10014
# scmutil.py - Mercurial core utility functions
#
# Copyright Matt Mackall <mpm@selenic.com> and other
#
# 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 . import repoview
def cachetocopy(srcrepo):
"""return the list of cache file valuable to copy during a clone"""
# In local clones we're copying all nodes, not just served
# ones. Therefore copy all branch caches over.
cachefiles = [b'branch2']
cachefiles += [b'branch2-%s' % f for f in repoview.filtertable]
cachefiles += [b'rbc-names-v1', b'rbc-revs-v1']
cachefiles += [b'tags2']
cachefiles += [b'tags2-%s' % f for f in repoview.filtertable]
cachefiles += [b'hgtagsfnodes1']
return cachefiles