one-line fix to #330

[jamescheney]

I was just reading #330 randomly, and wondered whether this one-line fix suffices. It does allow Daniel's example to be parsed:

links> sig f : () {:a,wild}-> () fun f() { () };
f = fun : () {:_}~> ()

but perhaps there are other negative consequences which are the reason this issue has been hanging around for over a year. @dhil?

[jamescheney]

This seems unproblematic, at least as far as existing tests are concerned. (the MacOS tests failed the first time for random-looking reasons.) Will merge Monday if there are no objections by then.

[dhil]

but perhaps there are other negative consequences which are the reason this issue has been hanging around for over a year. @dhil?

I don't think there are any negative consequences.

[jamescheney]

Closes #330