Run clippy on latest nightly that has clippy

Author: dtolnay

.travis.yml

@@ -15,8 +15,12 @@ matrix:
       script: cargo check
     - rust: 1.36.0
       script: cargo check --no-default-features
-    - rust: nightly
-      name: Clippy
+    - name: Clippy
+      install:
+        - CLIPPY_NIGHTLY=nightly-$(curl -s https://rust-lang.github.io/rustup-components-history/x86_64-unknown-linux-gnu/clippy)
+        - echo "Latest nightly with Clippy is $CLIPPY_NIGHTLY"
+        - rustup set profile minimal
+        - rustup default "$CLIPPY_NIGHTLY"
+        - rustup component add clippy
       script:
-        - rustup component add clippy || travis_terminate 0
         - cargo clippy -- -Dclippy::all