Fix alloc+std feature combination

Author: dhardy

.travis.yml

@@ -29,6 +29,7 @@ matrix:
         - pip install 'travis-cargo<0.2' --user && export PATH=$HOME/.local/bin:$PATH
       script:
         - cargo test --tests --no-default-features --features=alloc
+        - cargo test --all --features=alloc
         - cargo test --all --features serde-1,log,nightly
         - cargo test --benches
         - cargo doc --no-deps --all-features

src/lib.rs

@@ -1094,8 +1094,7 @@ pub fn sample<T, I, R>(rng: &mut R, iterable: I, amount: usize) -> Vec<T>
 mod test {
     use mock::StepRng;
     use super::*;
-    #[cfg(feature="alloc")]
-    use alloc::boxed::Box;
+    #[cfg(all(not(feature="std"), feature="alloc"))] use alloc::boxed::Box;
 
     pub struct TestRng<R> { inner: R }