Martin von Zweigbergk <martinvonz@google.com> [Thu, 19 Mar 2015 09:12:21 -0700] rev 24391
walkchangerevs: make followfilter a top-level class
The class only depends on the 'repo' variable in the closure, so let's
move the class out of the function and make it explicit that that (the
repo) is all it needs.