Message 79591 - Python tracker
Agreed, we failed to mention the behavior change in the docs. I'll take care of that. (if its mentioned at all, its mentioned in a note buried in the Misc/NEWS file somewhere) 2to3 could presumably be made to notice crc32 and adler32 calls and warn about this problem. I wouldn't have 2to3 add code to re-sign the return value by default as not everything needs that but it is worthy of a warning.