prev: add a test case which shows traceback when doing prev on obsolete cset
This patch adds a test which shows how `hg prev` is borken when called from a
obsolete changeset and there is an active topic. The next patch will fix 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