Currently, completing a release works with a plain git push. It may
push to several repos, depending on how the client repo's origin's
pushurl is configured. Those repos may have different user names, and
if the ssh wrapper added -l via JW_PKG_SSH_EXTRA_OPTS, the push would
fail. Hence, disable JW_PKG_SSH_EXTRA_OPTS for that case.
Signed-off-by: Jan Lindemann <jan@janware.com>