pstest: Fix pulling current patchset

* the output of the git ls-remote gets screwy after 9 commits, so fix the logic that is used to determine the most recent patchset

Change-Id: Idcf2075729eb175d4fbeb470060b8de26213d17a
Signed-off-by: Brandon McAnsh <brandon.mcansh@gmail.com>
Merge branch 'kitkat' of https://github.com/AOKP/build into kitkat