TEST: try to make launchscan test more robust

- got an assert failure (vol == 2, should have been 3, so it missed something, somewhere, one time, on travis... can't reproduce so this is just a guess)
ENH: better version of setUnits without logging (per Jonas)
Merge pull request #676 from jeremygray/master

tweak a test; better no-logging for Window.setUnits