Deactivate bazel caching for linux wheels (#5915)

Author: pcmoritz

.travis.yml

@@ -113,14 +113,20 @@ matrix:
         - ./ci/suppress_output ./ci/travis/install-dependencies.sh
 
         # Mount bazel cache dir to the docker container.
+        # For the linux wheel build, we use a shared cache between all
+        # wheels, but not between different travis runs, because that
+        # caused timeouts in the past. See the "cache: false" line below.
         - export MOUNT_BAZEL_CACHE="-v $HOME/ray-bazel-cache:/root/ray-bazel-cache -e TRAVIS=true"
+
         # This command should be kept in sync with ray/python/README-building-wheels.md,
         # except the `$MOUNT_BAZEL_CACHE` part.
+
         - ./ci/suppress_output docker run --rm -w /ray -v `pwd`:/ray $MOUNT_BAZEL_CACHE -ti rayproject/arrow_linux_x86_64_base:latest /ray/python/build-wheel-manylinux1.sh
       script:
         - if [ $RAY_CI_LINUX_WHEELS_AFFECTED != "1" ]; then exit; fi
 
         - ./ci/travis/test-wheels.sh
+      cache: false
 
     # Build MacOS wheels.
     - os: osx