Remove no need LOG.exception on attach_interface

When attach_interface, this LOG.exception will be reported
if InterfaceAttachFailed is raised from compute layer
actually, there already are LOG.error and API layer also
reported this exception, so there is no need to
raise exception here.

Change-Id: If5258c851b60cc4360f357a531610e4e52f9b26c

nova/api/openstack/compute/contrib/attach_interfaces.py

@@ -133,7 +133,6 @@ def create(self, req, server_id, body):
             msg = _("Network driver does not support this function.")
             raise webob.exc.HTTPNotImplemented(explanation=msg)
         except exception.InterfaceAttachFailed as e:
-            LOG.exception(e)
             msg = _("Failed to attach interface")
             raise webob.exc.HTTPInternalServerError(explanation=msg)
         except exception.InstanceInvalidState as state_error: