Shift Sprint Bug

You cant select 1.7.2 to i clicked on 1.7.9 but its 1.7.2, can't find another wbsite to report for 1.7.2

When i shift click 2 times really it sprints, almost every time because when you shift when you sprint it stops so it only works sometimes, i have looket at the controls menu and its fine no sprint set to shift, i don't think it would even work to change shift to 2 controls so yea.
thats all i think, cya
ooh and I'm using mac if that helps you (1.7.2)
Sorry for my terrible english, I'm from the home of Minecraft