Doctest broken by rustdoc in 1.53 nightly

[dtolnay]

Specifically this test:

seq-macro/src/lib.rs

Lines 44 to 60 in b9d1fd4

	//! ```
	//! use seq_macro::seq;
	//!
	//! seq!(N in 64..=127 {
	//! #[derive(Debug)]
	//! enum Demo {
	//! // Expands to Variant64, Variant65, ...
	//! #(
	//! Variant#N,
	//! )*
	//! }
	//! });
	//!
	//! fn main() {
	//! assert_eq!("Variant99", format!("{:?}", Demo::Variant99));
	//! }
	//! ```

rust-lang/rust#84445 changed rustdoc's handling of lines that begin with # not followed by whitespace. Previously the doc code compiled and rendered correctly as written, since the line #( was nothing special to rustdoc. After that PR, the doc code renders incorrectly:

seq!(N in 64..=127 {
    #[derive(Debug)]
    enum Demo {
        // Expands to Variant64, Variant65, ...
            Variant#N,
        )*
    }
});

and fails to compile, since rustdoc is trimming the #( into a hidden line containing only (:

---- src/lib.rs - (line 44) stdout ----
error: expected identifier, found `(`
  --> src/lib.rs:51:1
   |
9  | / (
10 | |             Variant#N,
11 | |         )*
   | |_________^ expected identifier

error[E0433]: failed to resolve: use of undeclared type `Demo`
  --> src/lib.rs:58:45
   |
16 |     assert_eq!("Variant99", format!("{:?}", Demo::Variant99));
   |                                             ^^^^ use of undeclared type `Demo`