fix msec format string

in the else case, which was triggered for devstack gate
the msec format string was incorrect, thus largely scrambling
the usefulness of logs. Fix this to make devstack readable.

Change-Id: I59d0e73932daf27dc1d718dfcf217fe2edf4d491
diff --git a/lib/nova b/lib/nova
index 21157dc..a43c091 100644
--- a/lib/nova
+++ b/lib/nova
@@ -414,7 +414,7 @@
         add_nova_opt "logging_exception_prefix=%(color)s%(asctime)s.%(msecs)d TRACE %(name)s %(instance)s"
     else
         # Show user_name and project_name instead of user_id and project_id
-        add_nova_opt "logging_context_format_string=%(asctime)s.%(msecs) %(levelname)s %(name)s [%(request_id)s %(user_name)s %(project_name)s] %(instance)s%(message)s"
+        add_nova_opt "logging_context_format_string=%(asctime)s.%(msecs)d %(levelname)s %(name)s [%(request_id)s %(user_name)s %(project_name)s] %(instance)s%(message)s"
     fi
     if is_service_enabled ceilometer; then
         add_nova_opt "instance_usage_audit=True"