tests/testlib/push-checkheads-util.sh

discovery: port _postprocessobsolete() changes from evolve, add tests

Let's make this function obsolescence-aware as well. Now we check that
revisions are not obsolete first, and only then check that they are going to be
common after exchange.

The tests make sure that rewriting changesets doesn't confuse head computation.
They rely on experimental.single-head-per-branch feature to show that remote
correctly sees the expected result (i.e. either aborts the push or allows it to
succeed). They are ported from evolve as well.

Differential Revision: https://phab.mercurial-scm.org/D12098

# setup config and various utility to test new heads checks on push

cat >> $HGRCPATH <<EOF
[command-templates]
# simpler log output
log ="{node|short} ({phase}): {desc}\n"

[phases]
# non publishing server
publish=False

[extensions]
# we need to strip some changeset for some test cases
strip=

[experimental]
# enable evolution
evolution=all

[alias]
# fix date used to create obsolete markers.
debugobsolete=debugobsolete -d '0 0'
EOF

mkcommit() {
   echo "$1" > "$1"
   hg add "$1"
   hg ci -m "$1"
}

getid() {
   hg log --hidden --template '{node}\n' --rev "$1"
}

setuprepos() {
    echo creating basic server and client repo
    hg init server
    cd server
    mkcommit root
    hg phase --public .
    mkcommit A0
    cd ..
    hg clone server client

    if [ "$1" = "single-head" ]; then
        echo >> "server/.hg/hgrc" "[experimental]"
        echo >> "server/.hg/hgrc" "# enforce a single name per branch"
        echo >> "server/.hg/hgrc" "single-head-per-branch = yes"
    fi
}