tests/hghave

narrow: add server logic to send cg while widening without ellipsis

Before this patch, if you try to widen a narrow clone without ellipsis enabled,
it will be broken and the exchange.pull() done by tracked command to widen the
clone will be no-op because no custom logic exists for this and server sees that
we have all csets and it says `no changes found`.

The widening with ellipsis send KILL for existing changegroups and send new
changegroups because of the change in ellipsis hash, but we can prevent that in
non-ellipsis cases.

This patch adds server side logic to send the changegroups for the changesets
which are on the client again with filelogs and manifests for the new includes.
This is a very starting implementation and we send changegroups and manifests
too while we can prevent them.

Following things can definitely be improved in the logic this patch adds:

  1) Send just the filelogs and treemanifests
  2) Send the filelogs only for the additions in the include

I tried 1) here but the code is coupled tightly and the way I was able to do
that was hacking into the changegroup generation code in a very dirty way, like
adding conditionals and preventing the yield.

This patch also adds a 'widen' kwarg to prevent other commands except widening
to go through that codepath.

The test changes demonstrate that the new implementation is correct and fixes
things.

Differential Revision: https://phab.mercurial-scm.org/D4383

#!/usr/bin/env python
"""Test the running system for features availability. Exit with zero
if all features are there, non-zero otherwise. If a feature name is
prefixed with "no-", the absence of feature is tested.
"""

from __future__ import absolute_import, print_function

import hghave
import optparse
import os
import sys

checks = hghave.checks

def list_features():
    for name, feature in sorted(checks.items()):
        desc = feature[1]
        print(name + ':', desc)

def test_features():
    failed = 0
    for name, feature in checks.items():
        check, _ = feature
        try:
            check()
        except Exception as e:
            print("feature %s failed:  %s" % (name, e))
            failed += 1
    return failed

parser = optparse.OptionParser("%prog [options] [features]")
parser.add_option("--test-features", action="store_true",
                  help="test available features")
parser.add_option("--list-features", action="store_true",
                  help="list available features")

def _loadaddon():
    if 'TESTDIR' in os.environ:
        # loading from '.' isn't needed, because `hghave` should be
        # running at TESTTMP in this case
        path = os.environ['TESTDIR']
    else:
        path = '.'

    if not os.path.exists(os.path.join(path, 'hghaveaddon.py')):
        return

    sys.path.insert(0, path)
    try:
        import hghaveaddon
        assert hghaveaddon  # silence pyflakes
    except BaseException as inst:
        sys.stderr.write('failed to import hghaveaddon.py from %r: %s\n'
                         % (path, inst))
        sys.exit(2)
    sys.path.pop(0)

if __name__ == '__main__':
    options, args = parser.parse_args()
    _loadaddon()
    if options.list_features:
        list_features()
        sys.exit(0)

    if options.test_features:
        sys.exit(test_features())

    hghave.require(args)