The ebuild for app-admin/salt-9999 is a straight copy of app-admin/salt-2014.7.0, so it tries to apply the patch "${FILESDIR}/salt-9999-remove-pydsl-includes-test.patch" which doesn't exist. As upstream's code of "tests/unit/pydsl_test.py" in the 'develop' branch hasn't diverted from '2014.7' yet, simply creating this patch as a copy of the 2014.7 patch works just fine.
I just dropped the patch, I am not going to maintain patches to try to keep tests passing in the 9999 ebuild.