evolvecmd: _possibledestination() skip visiting empty parent
I see that even in the case when "parent == -1" we are visiting
that also and find succsets for that and in last -1 is being
added in the set of possible destination. Why not skip that?
# utility to setup pythonpath to point into the tested repository
export SRCDIR=`dirname $TESTDIR`
if [ -n "$PYTHONPATH" ]; then
export HGTEST_ORIG_PYTHONPATH=$PYTHONPATH
export PYTHONPATH=$SRCDIR:$PYTHONPATH
else
export PYTHONPATH=$SRCDIR
fi