patchew-importer: import Maildir into Patchew before syncing IMAP
patchew-importer: import Maildir into Patchew before syncing IMAP

This is more effective when the container is stopped and restarted in
the middle of an importer run.  Previously, all the messages on the
IMAP server would be imported again and again, causing sort of a
quadratic behavior.

Now, instead, the messages are deleted on the maildir as soon as the
container is restarted, and the subsequent offlineimap run will both
delete them and read new messages.

Reviewed-by: Fam Zheng <3fda8cf018b542f405493d78ea980b2545014644@euphon.net>
Signed-off-by: Paolo Bonzini <69d3ebcf5ee4e7f05a50dc23cd96655b730804b4@redhat.com>

patchew-project/patchew,patchew-project/patchew,patchew-project/patchew,patchew-project/patchew