definite data corruption in 2.5.0 with -z option

[rsync at ka9q.net]

I just confirmed that data corruption can occasionally occur with
rsync 2.5.0 when the -z option is used. My command was the following:

rsync -vaz --partial --block-size=65536 --checksum remote:/path/ /localdir

The files consisted of a year's worth of email (262MB), broken into
one file for each day.

At least this doesn't seem to occur silently; I get the message
"ERROR: file corruption in foo. File changed during transfer?".
This happened for 5 files out of 358 total.

Repeated rsyncs yield the same message for the same files, and manual
md5sums confirm that the files mentioned in the messages differ. When
I repeated the rsync without the -z option, the transfers completed
normally and the md5sums then matched.

Each end is running Debian Potato with zlib1g and zlib1g-dev version
1.1.3-5.

Phil