Fixes a problem with unclosed streams

The streams don't get closed during processing and so stay open and thus cause the test ReplicationTest/testPushReplicationCanMissDocs to fail on Windows but more general mean that anytime, anyone ever uses multi-part (which is used, for example, by the pusher) then the streams will be locked forever and attachment cleanup isn't possible.
EEEK!!!! Well that is an embarrassing mistake. Thank you for catching it before it got checked in! I'll update now.