The bug caused a segfault and you can find more info about it at:
https://bugs.ruby-lang.org/issues/10685.

We did a couple of work arounds, but 2.2.1 rolled out and those aren't
needed anymore.

Here are the reverted commits:

- Revert "Work around for upstream Ruby bug #10685",
  commit 707a4338.

- Revert "Fix segmentation fault in ActionPack tests",
  commit 22e0a22d.

I'm also bumping the Ruby version check to 2.2.1 to prevent future
segfaults.