Just removing this line gives me:

maciej@maciej-vaio ~/g/coreutils> make BUILD=kill
sh -c 'rustc --opt-level=3 -o build/kill kill/kill.rs'
kill/kill.rs:34:5: 34:12 error: unresolved import. maybe a missing `extern crate signals`?
kill/kill.rs:34     ALL_SIGNALS,
                    ^~~~~~~
kill/kill.rs:34:5: 34:16 error: failed to resolve import `signals::ALL_SIGNALS`
kill/kill.rs:34     ALL_SIGNALS,
                    ^~~~~~~~~~~
kill/kill.rs:35:5: 35:12 error: unresolved import. maybe a missing `extern crate signals`?
kill/kill.rs:35     DEFAULT_SIGNAL,
                    ^~~~~~~
kill/kill.rs:35:5: 35:19 error: failed to resolve import `signals::DEFAULT_SIGNAL`
kill/kill.rs:35     DEFAULT_SIGNAL,
                    ^~~~~~~~~~~~~~
error: aborting due to 4 previous errors
make: *** [build/kill] Error 101
maciej@maciej-vaio ~/g/coreutils> rustc -v
rustc 0.10-pre
host: x86_64-unknown-linux-gnu


I am testing it on nightly build from ubuntu ppa.