[Bug] Missing Disk Pool throws 500 instead 404

[dvjsharma]

Summary

When invoking guest_add_disks with a non-existent disk pool (e.g. "ECKD:notexist"), the SDK currently responds with HTTP 500 but should return HTTP 404. Internally, the SMUT handler maps missing pools to a 404 condition, but the WSGI layer does not propagate this status code or update the response body accordingly.

Error

Request body:
'[{u'disk_pool': u'ECKD:notexist', u'size': u'1g'}]' for guest 'RST95754'.

Error msg:
{u'rs': 402, u'overallRC': 4, u'modID': 1, u'rc': 5, u'output': u'', u'errmsg': u"SMUT error: SMUT request failed. RequestData: 'getHost diskpoolspace noexist', Results: '{'rs': 402, 'errno': 0, 'strError': '', 'overallRC': 4, 'rc': 5, 'response': ['(Error) ULTGHO0402E No information was found for the specified pool(s): noexist']}'"}

It should return 404 if specified disk pool not exists.

Launchpad Ref - https://bugs.launchpad.net/python-zvm-sdk/+bug/1747591