Downgrade target create failure mesg to warning

Since this will occur more often than we would like and
almost always recovers, change the log level to warning
instead of error.

This is to comply with the desire of the QA team to eradicate
error messages from succesful tempest runs.

Change-Id: If1a841bbeb9a36ff7e103a0e9aff67fda66a7f3b
Closes-Bug: #1243840

cinder/brick/iscsi/iscsi.py

@@ -207,9 +207,9 @@ def create_iscsi_target(self, name, tid, lun, path,
                                        run_as_root=True)
             LOG.debug("Targets after update: %s" % out)
         except putils.ProcessExecutionError as e:
-            LOG.error(_("Failed to create iscsi target for volume "
+            LOG.warning(_("Failed to create iscsi target for volume "
                         "id:%(vol_id)s: %(e)s")
-                      % {'vol_id': vol_id, 'e': str(e)})
+                        % {'vol_id': vol_id, 'e': str(e)})
 
             #Don't forget to remove the persistent file we created
             os.unlink(volume_path)