From: Mark Brown <broonie@sirena.org.uk>
Currently offlineimap will attempt to connect to the first address
returned by addrinfo() for the remote system and will fail if that fails
even if another result would have worked. This is particularly common
when the remote system supports both IPv4 and IPv6 - a laptop may in
some environments have no routable IPv6 connectivity so if the IPv6
address is returned first the connect will fail even though IPv4 would
have worked.
This is actually a bug in imaplib, a copy of which is included in
offlineimap. This patch fixes the problem by looping over all the
results returned by getaddrinfo(). Unfortunately it mangles the error
reporting slightly since I couldn't work out how to raise an appropriate
exception, though given that that that was a Python backtrace there was
work to do there anyway.