FIX Avoid compressing files twice when deploying

[rth]

Closes #1764

With the previous version of the find -exec ... command what seems to be happening is that as files are compressed and renamed, find considers these to be new files and re-applies exec again. This would have been avoided if we kept the .gz extension (gzip refuses to compress .gz files) but since we need to preserve the file name, there is no way to detect it. No idea why it only happens with some files.

I can't find much existing discussions about this behavior but it's what I observe empirically. Moving to a find -print0 | xargs -0 -n1 should fix it.

Skipping CI, since this will only run for deployment (and I tested it in the Circle CI job)