On iSCSI connections that make use of discovery we will be obscuring the
the logs if the sendtargets command fails because when we try to do the
cleanup another exception will be raised (TargetPortalsNotFound).
The original exception is still logged since we are using
excutils.save_and_reraise_exception(), but it will be misleading if we
don't pay close attention.
This patch fixes this by ignoring the 'Unable to find target portals
information on discoverydb.' error, but logging a debug log message,
when doing the cleanup because this exception means that the sendtargets
failed and therefore we don't have anything to cleanup.
Change-Id: I7ddf827c7f2285acd72fd5a2fcd351928cb5d2df
8e4adda001