Fix the entry condition of Bazel hack

src/python/grpcio_tests/tests/bazel_namespace_package_hack.py

@@ -16,6 +16,8 @@ import os
 import site
 import sys
 
+_GRPC_BAZEL_RUNTIME_ENV = "GRPC_BAZEL_RUNTIME"
+
 
 # TODO(https://github.com/bazelbuild/bazel/issues/6844) Bazel failed to
 # interpret namespace packages correctly. This monkey patch will force the
@@ -24,6 +26,9 @@ import sys
 # Analysis in depth: https://github.com/bazelbuild/rules_python/issues/55
 def sys_path_to_site_dir_hack():
     """Add valid sys.path item to site directory to parse the .pth files."""
+    # Only run within our Bazel environment
+    if not os.environ.get(_GRPC_BAZEL_RUNTIME_ENV):
+        return
     items = []
     for item in sys.path:
         if os.path.exists(item):

tools/bazel.rc

@@ -5,6 +5,7 @@
 
 build --client_env=CC=clang
 build --copt=-DGRPC_BAZEL_BUILD
+build --action_env=GRPC_BAZEL_RUNTIME=1
 
 build:opt --compilation_mode=opt
 build:opt --copt=-Wframe-larger-than=16384