rand fails to migrate

[nikomatsakis]

@teiesti helpfully reported that rand fails to migrate successfully:

branch here

$ cargo +nightly build
   Compiling rand v0.5.0 (file:///home/tobias/dev/rand)
error[E0463]: can't find crate for `distributions`
   --> src/distributions/uniform.rs:104:5
    |
104 | use distributions::Distribution;
    |     ^^^^^^^^^^^^^ can't find crate

error: aborting due to previous error

[Mark-Simulacrum]

I successfully migrated rand after some minor edits to macros (::core being replaced with crate::core); so I'm going to close this issue.