scribble/comment-reader and quasiquote

[dvanhorn]

The scribble/comment-reader causes quasiquote (#\u60) to be replaced by a left single quotation mark (#\u2018), which is inconsistent with what other comment forms produce. For example, the first two produce the right thing, but the last doesn't:

#lang scribble/manual
@(require scribble/examples)

@racketblock[(code:comment "`hi")]
@examples[(code:comment "`hi")]
@#reader scribble/comment-reader
(racketblock
;; `hi
)