we try to load the correct media in a loop until we find the correct tape.
when encountering an error or wrong tape, we want to log that (and send
an email if one is set) that requests the correct tape.
while trying to avoid printing the same errors more than once in a row,
we had at least one case (starting with an empty tape in the drive)
which would not print/send any tape request.
reworking that code to use a custom 'TapeRequest' enum, which contains
the state + error message, and a helper that prints and sends an email
when the state changes
this reduces the change check/log to a single variable, instead of 4
(tried, last_media_uuid, last_error, failure_reason)
Signed-off-by: Dominik Csapak <d.csapak@proxmox.com>
Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>