> I noted this in the PR description 

Clearly I need to read the PR descriptions better and not just dive in to the code review :).

> I could initially refactor it to match deprecation.rb, then add this change next? I have a spec for it in xspec, should be able to port that over.

In general that sounds good, but it's unclear to me how what you have here is better than the regex, particularly given that it's not doing the same thing: you are starting with an array and removing entries; we're simply looking for the first array entry that doesn't match a pattern.  Ultimately, I don't have a particular maintenance preference of using a construct like `start_with?` over a regex, so to me it comes down to perf: which is faster in a benchmark?