stablerange: compute subranges from parent when possible
Unless we are a merge, we can infer the standard subranges of a range by reusing
the subranger of its parent. We update the implementation to do so.
We still needs the "old way" for merge. We move that code in a dedicated
function for the sake of simplicity.
#!/bin/sh
# This file holds logic that is used in many tests.
# It can be called in a test like this:
# $ . "$TESTDIR/testlib/topic_setup.sh"
# Enable obsolete markers and enable extensions
cat >> $HGRCPATH << EOF
[experimental]
evolution=createmarkers,exchange
[extensions]
rebase=
EOF
echo "topic=$(echo $(dirname $TESTDIR))/hgext3rd/topic" >> $HGRCPATH