Bug: Regression: comment position in list patterns

[jberdine]

Describe the bug
#866 introduced a regression in the position of comments in list patterns.

How to Reproduce
Executing

$ echo "let [(* comment one *) one; (* comment two *) two] = [1; 2]" | _build/default/src/ocamlformat.exe --name "foo.ml" -

produces

let (* comment one *) [one; (* comment two *) two] = [1; 2]

while it should, and used to, produce

let [(* comment one *) one; (* comment two *) two] = [1; 2]