imaplibutil: Have SELECT throw an OfflineImapError when the connection died
imaplibutil: Have SELECT throw an OfflineImapError when the connection died

Imapserver.acquireconnection will succeed even whent the server connection
has been terminated and the first IMAP operation will throw an exception.

Often this is the folder SELECT operation (e.g. after an idle timeout), as
has been reported by John Wiegley. Catch this case and throw an
OfflineImapError with severity FOLDER_RETRY to notify consumers that they
are supposed to retry.

Signed-off-by: Sebastian Spaeth <98dcb2717ddae152d5b359c6ea97e4fe34a29d4c@SSpaeth.de>
Signed-off-by: Nicolas Sebrecht <347709267ddd1958560c4c317ea3fd613f10a719@laposte.net>

frioux/offlineimap,frioux/offlineimap