Shopify/batman — pull request #565 by loopj (2012-10-09 22:03:00+00:00)
Title: Prevent unnecessary additional history items from being created from pushState

Prevent additional history items from being created if the users navigates to the page they are already on.

This ensures that `pushState` acts exactly like normal browser navigation.
Try it yourself, clicking on a normal non-pushState link that repeatedly takes you to the same URL does not create additional history items.