build: do not cache clippy binaries in integration tests

We rebuild clippy anyway.

.travis.yml

@@ -13,8 +13,8 @@ cache:
     - $HOME/.cargo
 before_cache:
   - cargo install -Z install-upgrade cargo-cache --debug
-  - cargo cache --autoclean
   - find $HOME/.cargo/bin/ ! -type d -exec strip {} \;
+  - cargo cache --autoclean
 
 env:
  global:

ci/integration-tests.sh

@@ -28,6 +28,7 @@ cargo clippy \
     -W clippy::nursery \
     > clippy_output 2>&1 || true
 
+cargo uninstall clippy
 cat clippy_output
 
 if grep -q "internal compiler error\|query stack during panic\|E0463" clippy_output; then