Fix stuck changes reader in clean_mailbox
Due to unfortunate timing issues it was possible for a changes reader to
get stuck in clean_mailbox reading an entire changes feed before
exiting. If the ibrowse call timed out right before ibrowse starts
sending messages then we would see clean_mailbox loop until the changes
feed terminated on the source.
This caps the number of messagses that can be cleaned up to a maximum of
sixteen. This limit is rather arbitrary. The cleanup was intended for when
only a couple messages were lingering. This is much larger than that
without being insanely large.
BugzId: 49717
1 file changed
