systemd not happy with long postscript

[Diaoul]

Since #111 it is possible to run long-standing processes within autorandr postscript. I use this to re-run my bspwmrc that will rearrange deskops on my monitors and the polybars. However, this seems to cause some warnings visible in journalctl -u autorandr

Jun 20 22:27:01 xxx systemd[1]: autorandr.service: Found left-over process 7085 (bash) in control group while starting unit. Ignoring.
Jun 20 22:27:01 xxx systemd[1]: This usually indicates unclean termination of a previous run, or service implementation deficiencies.
[...]

What is the best practice to avoid this? Maybe have autorandr trigger a reload rather than doing the reloading itself?