fix bazel wrapper download race in sanity tests

tools/bazel

@@ -24,12 +24,20 @@
 
 set -e
 
-# First of all, if DISABLE_BAZEL_WRAPPER is set, just use BAZEL_REAL as set by
-# https://github.com/bazelbuild/bazel/blob/master/scripts/packages/bazel.sh
-# that originally invoked this script.
-if [ "${BAZEL_REAL}" != "" ] && [ "${DISABLE_BAZEL_WRAPPER}" != "" ]
+# DISABLE_BAZEL_WRAPPER can be set to eliminate the wrapper logic
+if [ "${DISABLE_BAZEL_WRAPPER}" != "" ]
 then
-  exec -a "$0" "${BAZEL_REAL}" "$@"
+  if [ "${BAZEL_REAL}" != "" ]
+  then
+    # use BAZEL_REAL as set by
+    # https://github.com/bazelbuild/bazel/blob/master/scripts/packages/bazel.sh
+    # that originally invoked this script (this is what happens when you
+    # run "bazel" in our workspace)
+    exec -a "$0" "${BAZEL_REAL}" "$@"
+  else
+    # if BAZEL_REAL is not set, just invoke the default system bazel
+    exec bazel "$@"
+  fi
 fi
 
 VERSION=1.0.0

tools/run_tests/run_tests.py

@@ -1243,6 +1243,11 @@ class Sanity(object):
             if _is_use_docker_child():
                 environ['CLANG_FORMAT_SKIP_DOCKER'] = 'true'
                 environ['CLANG_TIDY_SKIP_DOCKER'] = 'true'
+                # sanity tests run tools/bazel wrapper concurrently
+                # and that can result in a download/run race in the wrapper.
+                # under docker we already have the right version of bazel
+                # so we can just disable the wrapper.
+                environ['DISABLE_BAZEL_WRAPPER'] = 'true'
             return [
                 self.config.job_spec(cmd['script'].split(),
                                      timeout_seconds=30 * 60,