better fix for zombie problem, which turns out to be a zombie ssh started by rsync

When rsyncProgress pipes rsync's stdout, this turns out to cause a ssh
process started by rsync to be left behind as a zombie. I don't know why,
but my recent zombie reaping cleanup was correct, it's just that this other
zombie, that's not directly started by git-annex, was no longer reaped
due to changes in the cleanup. Make rsyncProgress reap the zombie started
by rsync, as a workaround.

FWIW, the process tree looks like this. It seems like the rsync child
is for some reason starting but not waiting on this extra ssh process.
Ssh connection caching may be involved -- disabling it seemed to change
the shape of the tree, but did not eliminate the zombie.

 9378 pts/14   S+     0:00  |           \_ rsync -p --progress --inplace -4 -e 'ssh' '-S' ...
 9379 pts/14   S+     0:00  |           |   \_ ssh ...
 9380 pts/14   S+     0:00  |           |   \_ rsync -p --progress --inplace -4 -e 'ssh' '-S' ...
 9381 pts/14   Z+     0:00  |           \_ [ssh] <defunct>

Command/Log.hs

@@ -70,7 +70,7 @@ start :: M.Map UUID String -> TimeZone -> [CommandParam] -> Bool ->
 start m zone os gource file (key, _) = do
 	showLog output =<< readLog <$> getLog key os
 	-- getLog produces a zombie; reap it
-	liftIO Git.Command.reap
+	liftIO reapZombies
 	stop
 	where
 		output