New git-utimes is broken on Mac

[spacewander]

When I run git-utimes on Mac, I get this error:

awk: cmd. line:10: fatal: not enough arguments to satisfy format string
	` t=$(date %s$1 "+%Y%m%d%H%M.%S")
'
	                     ^ ran out for this one

CC @rasa

[rasa]

@spacewander Thanks for the catch! I didn't have a Mac to test this, but now I do, and I tested my latest commit on it and can confirm it fixes this issue. The issue was I hadn't doubled the %s in the date format string for printf.