Build failing with 'can't find crate for gl_generator'

[guycook]

Both when trying to compile gfx-rs and then building gfx_gl by itself I am receiving the following error:

$ pwd
/home/guy/code/rust/gfx_gl

$ rustc --version
rustc 0.13.0-nightly (96a3c7c6a 2014-12-23 22:21:10 +0000)

$ cargo --version
cargo 0.0.1-pre-nightly (e11c317 2014-12-21 20:43:45 +0000)

$ cargo build --verbose
   Compiling gfx_gl v0.1.0 (file:///home/guy/code/rust/gfx_gl)
     Running `rustc build.rs --crate-name build-script-build --crate-type bin -C prefer-dynamic -g --out-dir /home/guy/code/rust/gfx_gl/target/build/gfx_gl-97b9a2a3dbbf7312 --emit=dep-info,link -L /home/guy/code/rust/gfx_gl/target -L /home/guy/code/rust/gfx_gl/target/deps`
build.rs:1:1: 1:27 error: can't find crate for `gl_generator`
build.rs:1 extern crate gl_generator;
           ^~~~~~~~~~~~~~~~~~~~~~~~~~
error: aborting due to previous error
Could not compile `gfx_gl`.

Caused by:
  Process didn't exit successfully: `rustc build.rs --crate-name build-script-build --crate-type bin -C prefer-dynamic -g --out-dir /home/guy/code/rust/gfx_gl/target/build/gfx_gl-97b9a2a3dbbf7312 --emit=dep-info,link -L /home/guy/code/rust/gfx_gl/target -L /home/guy/code/rust/gfx_gl/target/deps` (status=101)