[#498] Dry up OPTIONS regression

[etehtsea]

This pull request broke OPTIONS for endpoints mounted inside root app with version.

Link to demo app

[dblock]

Could you please write a test for this in Grape proper? Appreciate it.

[dblock]

cc: @karlfreeman

[etehtsea]

@dblock I added failing spec, but I need feedback where the proper place for it and how to name it.

[dblock]

I think its location is fine. Now can you fix it? :)

[karlfreeman]

Thought I'd chime in on this.

Giving this a quick look at, I'm able to reproduce the error with this test karlfreeman@109d4e3 (eg the first test passes, whereas the second doesn't). It appears that using path versioning with a mounted api fails. I'm not going to be able to commit the time to fix this but figured I'd see if it was something simple.