This does not seem like a nova bug. As per the error that was extracted in comment #3 (thanks Matthew) - this error occurs when nova cannot find the iscsi device after CONF.num_iscsi_scan_tries (by default 3), sleeping try_no ** 2 secs in between - so 14 secs by default. A simple solution might be to increase this limit for tempest runs.
This does not seem like a nova bug. As per the error that was extracted in comment #3 (thanks Matthew) - this error occurs when nova cannot find the iscsi device after CONF.num_ iscsi_scan_ tries (by default 3), sleeping try_no ** 2 secs in between - so 14 secs by default. A simple solution might be to increase this limit for tempest runs.