`ERROR:rustc_lint::builtin: span mc spanspam` when compiling clippy_lints

[Arnavion]

rustc 1.19.0-nightly (d3abc80b3 2017-05-09)

$ cargo install -j1 --force clippy
<snip successful compilation of other deps>
   Compiling clippy_lints v0.0.131
ERROR:rustc_lint::builtin: span mc spanspam
ERROR:rustc_lint::builtin: span mc spanspam
ERROR:rustc_lint::builtin: span mc spanspam
ERROR:rustc_lint::builtin: span mc spanspam
<snip successful compilation of clippy>

The message was introduced in rust-lang/rust@de7dda7#diff-1651ba5b47f9ffa648d59265d3f94becR721 by rust-lang/rust#41293

It compiles successfully so it's not a big problem. Just seems to be some lint firing against float literals in patterns in clippy_lints (perhaps https://github.com/Manishearth/rust-clippy/blob/3b3e47f4/clippy_lints/src/zero_div_zero.rs#L41-L42 ?)