More cleanly error on unknown media

Rather than raise ugly unexpected
errors and pollute trace log,
cleanly handle the likelihood
of unknown media.

confluent_server/bin/osimage

@@ -184,7 +184,8 @@ def osimport(imagefile):
             else:
                 print(repr(rsp))
             time.sleep(0.5)
-    list(c.delete('/deployment/importing/{0}'.format(shortname)))
+    if shortname:
+        list(c.delete('/deployment/importing/{0}'.format(shortname)))
 
 if __name__ == '__main__':
     main(sys.argv)

confluent_server/confluent/osimage.py

@@ -1,4 +1,5 @@
 #!/usr/bin/python
+import confluent.exceptions as exc
 import confluent.messages as msg
 import eventlet
 import eventlet.green.select as select
@@ -428,6 +429,8 @@ class MediaImporter(object):
         self.worker = None
         self.profiles = []
         identity = fingerprint(media)
+        if not identity:
+            raise exc.InvalidArgumentException('Unsupported Media')
         self.percent = 0.0
         identity, _ = identity
         self.phase = 'copying'