only trigger a warning on failure, since they should not stop backups
from being done. Also migrated full/incremental backup switch to the
new syntax.
+ . Support every duplicity-supported transport with new configuration
+ option desturl (Closes: #483712, #346040, Trac#2).
ldap:
. support HDB backend just as the BDB one, and make message clearer
when no supported backend is found (Closes: #476910)