topics: fix `hg stack` in case of split
This patch fixes the behaviour of hg stack which throws an error in some cases
when there are multiple successors. The case of divergence is not handled yet.
#require test-repo
$ checkcm() {
> if ! (which check-manifest > /dev/null); then
> echo skipped: missing tool: check-manifest;
> exit 80;
> fi;
> };
$ checkcm
$ cat << EOF >> $HGRCPATH
> [experimental]
> evolution=all
> EOF
Run check manifest:
$ cd $TESTDIR/..
$ check-manifest
lists of files in version control and sdist match