zip_archive: reject files that don't start with an LFH signature. am: 2740bb09e3 am: 61f846b71c am: 45931c5e03 am: b1b91cff95 am: a2dc43197d  -s ours
am: edccf1c133  -s ours

Change-Id: I4320e562175130e24b32b98cffb73cfd763cc90c