Fix for Rubinius 2.0

[wulftone]

I ran into a problem where this gem wasn't working when I wanted to switch to Rubinius, so I tracked this down and fixed it.

Since this relies on monkeypatching a function (_parse), that a user wouldn't normally call, and internally Rubinius uses a different arity on _parse, I think this patch is probably a good idea. : ) What do you think?

[jeremyevans]

Date._parse is a public method, and users would usually call it if they want to get a hash of values as opposed to a Date instance (I do this in Sequel to check if the date string contains an offset). I think adding additional optional arguments changes the API, and I'm not sure that's something they want to be doing.

Have you confirmed with the Rubinius developers that this is not going to change? I'm guessing they are having Date.parse call Date._parse with this flag set, instead of having both methods call a separate internal method (which would be the safer approach).

Assuming this behavior is not going to change, a more robust approach would be to check the arity of _parse_without_american_date instead of assuming 3 arguments on rbx.

[wulftone]

Yeah, that makes sense. I don't know if they're aware of it... I'll see what they have to say.

[wulftone]

They appear to be doing something. I'll just close this now. rubinius/rubinius#2241