Submitted by: Claudio Valderrama C. (robocop)

Assigned to: Claudio Valderrama C. (robocop)

When nbackup finds failure, it reports with an exception the cause of the failure.
However, in the cleanup process, it may cause an exception when trying to detach from the db, rollback a transaction, etc.
The user is interested in the main reason of failure and therefore, cleanup errors should be concealed unless they are caused under normal termination (and no other errors are being processed already).

Commits: 08a33d5