prelude_import should be unstable?

[nrc]

cc @chris-morgan, @eddyb

If this is a bug, we should fix it asap.

[eddyb]

@brson can the impact be estimated without merging a patch to make #[prelude_import] unstable?

[eddyb]

If GitHub search is to be believed, the only uses of #[prelude_import] appear in the compiler and in pretty-printed output.

[brson]

I've got a crater run of @eddyb's pr started.