Don't check rustfmt on nightly in CI (#676)

Author: max-sixty

.travis.yml

@@ -27,9 +27,5 @@ addons:
     packages:
       - libopenblas-dev
       - gfortran
-before_script:
-  - rustup component add rustfmt
 script:
-  - |
-    cargo fmt --all -- --check &&
-    ./scripts/all-tests.sh "$FEATURES" "$CHANNEL"
+  - ./scripts/all-tests.sh "$FEATURES" "$CHANNEL"

scripts/all-tests.sh

@@ -6,6 +6,7 @@ set -e
 FEATURES=$1
 CHANNEL=$2
 
+([ "$CHANNEL" != "beta" ] || (rustup component add rustfmt && cargo fmt --all -- --check))
 cargo build --verbose --no-default-features
 cargo test --verbose --no-default-features
 cargo test --release --verbose --no-default-features