-* timer logic is confused by units which are skipped due to failing condition
- http://lists.freedesktop.org/archives/systemd-devel/2013-February/008816.html
-
-* timer logic is also confused if a service it triggers hasn't finished when the next timer elapses:
- http://lists.freedesktop.org/archives/systemd-devel/2013-February/009021.html
-