changegroup: populate _clnodetorev as part of changelog linknode lookup
The thing that matters is that self._clnodetorev is populated with
changesets that are being sent. Back when this code was in an
extension, it wasn't possible to monkeypatch the changelog lookup
function. Now that the code is in core, we can move this code to
where it logically belongs.
Differential Revision: https://phab.mercurial-scm.org/D4186
node = <module 'mercurial.node' from '?'>
errorproxy = <unloaded module 'error'>
errorproxy.__doc__ = 'Mercurial exceptions. This ...'
errorproxy.__name__ = 'mercurial.error'
errorproxy.__dict__['__name__'] = 'mercurial.error'
errorproxy = <proxied module 'error'>
os = <unloaded module 'os'>
os.system = <built-in function system>
os = <module 'os' from '?'>
procutil = <unloaded module 'procutil'>
procutil.system = <function system at 0x?>
procutil = <module 'mercurial.utils.procutil' from '?'>
procutil.system = <function system at 0x?>
hgweb = <unloaded module 'hgweb'>
hgweb_mod = <unloaded module 'hgweb_mod'>
hgweb = <module 'mercurial.hgweb' from '?'>
fred = <unloaded module 're'>
remod = <unloaded module 're'>
re = <unloaded module 'sys'>
fred = <unloaded module 're'>
fred.sub = <function sub at 0x?>
fred = <proxied module 're'>
remod = <module 're' from '?'>
re = <unloaded module 'sys'>
re.stderr = <open file '<whatever>', mode 'w' at 0x?>
re = <proxied module 'sys'>
contextlib = <unloaded module 'contextlib'>
contextlib.unknownattr = ImportError: cannot import name unknownattr
__import__('contextlib', ..., ['unknownattr']) = <module 'contextlib' from '?'>
hasattr(contextlibimp, 'unknownattr') = False