[Dovecot] Order of operations in Dovecot

[Eric Gregory]

Hi, I'm working on an IMAP client and had a question about the order in
which commands are responded to in Dovecot.

In other IMAP servers I've looked at, when you issue two commands
simultaneously (i.e. pipelining) it looks something like this:

a fetch something
b fetch something else
* 1 FETCH (result)
a OK FETCH completed
* 1 FETCH (result)
b OK FETCH completed

This works well because it's clear which results are associated with which
tag; the 'a' fetch results immediately precede the a's OK response, and
likewise the 'b' fetch results immediately precede the b's OK response.

But in Dovecot (version 2.0.13) the results of the two simultaneous
commands are ordered like this:

a fetch something
b fetch something else
* 1 FETCH (result)
* 1 FETCH (result)
a OK FETCH completed
b OK FETCH completed

This makes associating the results of the fetch commands quite a bit more
difficult, since it's not entirely clear which results are paired with
which tag.

My question is this: is this Dovecot's intended behavior, or did I find a
bug?  I realize the IMAP spec is really vague about this.  If this is the
intended behavior, is there any advice for clients on how to determine
which results are associated with which command?

Thanks!
 - Eric