Nexus 7 grouper, manual update fails

I have a Nexus 7 (2012, grouper) which so far I have kept on 4.1.2 (JZO54K) using FOTAkill, but now I want to update to 4.2.2. I also have the latest CWM recovery (6.0.4.3).

I plan on applying successively:
094f6629314a.signed-nakasi-JOP40C-from-JZO54K.094f6629.zip
then
659e6288b87d.signed-nakasi-JOP40D-from-JOP40C.659e6288.zip
then
6ece895ecb23.signed-nakasi-JDQ39-from-JOP40D.6ece895e.zip

Using ADB I tried to apply the first update, but it fails. I also tried applying it from /sdcard, but the same thing happens. The error message happens after "verifying current system..." and it consists of:
assert failed: apply_patch_check("/system/app/Browser/ProviderProxy.odex", "21a896ab...
E: Error in /data/media/094f6629314a.signed-nakasi-JOP40C-from-JZO54K.094f6629.zip
(status 7)

I tried downloading the zip update again, but it still fails. I downloaded it from http://android.clients.google.com/pa...K.094f6629.zip