merge: store commitinfo if these is a dc or cd conflict delete-changed or changed-delete conflicts can either be resolved by mergetool, if some tool is passed and using or by user choose something on prompt or user doing some `hg revert` after choosing the file to remain conflicted. If the user decides to keep the changed side, on commit we just reuse the parent filenode. This is mostly fine unless we are in a distributed environment and people are doing criss-cross merges. Since, we don't have recursive merges or any other way of describing the end result of the merge was an explicit choice and it should be differentiated from it's ancestors, merge algo during criss-cross merges fails to take in account the explicit choice made by user and end up with a what-can-be-said-wrong-merge. The solution which we are trying to fix this is by creating a filenode on commit instead of reusing the parent filenode. This helps differentiate between pre-merged filenode and post-merge filenode and kind of tells about the choice user made. To implement creating new filenode functionality, we store info about these files in mergestate so that we can read them on commit and force create a new filenode. Differential Revision: https://phab.mercurial-scm.org/D8988

from __future__ import absolute_import, print_function

import os
from mercurial import (
    dispatch,
    ui as uimod,
)
from mercurial.utils import stringutil

# ensure errors aren't buffered
testui = uimod.ui()
testui.pushbuffer()
testui.writenoi18n(b'buffered\n')
testui.warnnoi18n(b'warning\n')
testui.write_err(b'error\n')
print(stringutil.pprint(testui.popbuffer(), bprefix=True).decode('ascii'))

# test dispatch.dispatch with the same ui object
hgrc = open(os.environ["HGRCPATH"], 'wb')
hgrc.write(b'[extensions]\n')
hgrc.write(b'color=\n')
hgrc.close()

ui_ = uimod.ui.load()
ui_.setconfig(b'ui', b'formatted', b'True')

# we're not interested in the output, so write that to devnull
ui_.fout = open(os.devnull, 'wb')

# call some arbitrary command just so we go through
# color's wrapped _runcommand twice.
def runcmd():
    dispatch.dispatch(dispatch.request([b'version', b'-q'], ui_))


runcmd()
print("colored? %s" % (ui_._colormode is not None))
runcmd()
print("colored? %s" % (ui_._colormode is not None))