Misleading error message when theme ZIP exceeds post_max_size

[ocean90]

post_max_size is 32MB, now try to uploading a 40MB big ZIP.

You will get the Are you sure you want to do this? Please try again. message. But try again will not help.

Notice:
Warning: POST Content-Length of 47774864 bytes exceeds the limit of 33554432 bytes in Unknown on line 0

Patch to detect truncated POST requests

This happens when php stops listening to the request after post_max_size is reached. When that happens, the mime request cannot be properly decoded, so no post variables come through (including the nonce).

18474.diff​ will detect the problem when a nonce fails and will give the proper error message, but there's nothing we can do about it from within WP.