refmt prints invalid Reason code for annotated polymorphic variant values when parsing OCaml syntax

[hcarty]

$ echo 'let x : t = `Poly' | refmt --parse=ml
let x:  .t = (`Poly: t);

The type constraint is duplicated and gets a leading . on the lhs of the =, leading to invalid syntax. Reason 3.2.0 installed via opam.

[IwanKaramazow]

Hmm, this a serious bug. I'm fixing it, unacceptable.

[hcarty]

Thanks @iwankaramazow!