Right now, commands that work are "build" and "clean".
`rustpkg build` and `rustpkg clean` should work
for example:
$ cd ~/rust/src/librustpkg/testsuite/pass
$ rustpkg build hello-world
... some output ...
$ rustpkg clean hello-world
-------------
the following test packages in librustpkg/testsuite/pass:
* hello-world
* install-paths
* simple-lib
* deeply/nested/path
* fancy-lib
It fails on the following test packages:
* external-crate (no support for `extern mod` inference yet)
and should fail with proper error messages
on all of the test packages in librustpkg/testsuite/fail
* no-inferred-crates
