Can't find crate for `regex_macros` in doctest

I'm getting this weird issue since Monday, currently reproducible with:

$ rustc --version
rustc 1.0.0-nightly (47def3ef2 2015-04-13) (built 2015-04-13)
$ cargo --version
cargo 0.0.1-pre-nightly (72c2e3d 2015-04-10) (built 2015-04-12)

All the tests passed successfully, but in the doctest phase, it is reported that

src/ 3:23 error: can't find crate for `regex_macros`
src/ #![plugin(regex_macros)]

Is there anybody knows the reason for that? You can find the build on travis:

and the code on github:

Any suggestion is welcomed!

Known bug:

Looks like a fix is in the pipeline.

Thanks! I should check cargo's issue tracker first.