Propagate sys.path to Bazel PYTHONPATH for PEP 517 build isolation compatibility

Author: vkarampudi

setup.py

@@ -90,15 +90,22 @@ def run(self):
                 bazel_version = f.read().strip()
                 os.environ["USE_BAZEL_VERSION"] = bazel_version
 
+        pythonpath = os.environ.get("PYTHONPATH", "")
+        # Include sys.path entries to support PEP 517 isolated build environments
+        sys_path_entries = os.pathsep.join([p for p in sys.path if p])
+        if pythonpath:
+            pythonpath = os.pathsep.join([pythonpath, sys_path_entries])
+        else:
+            pythonpath = sys_path_entries
+
         bazel_args = [
             self._bazel_cmd,
             "run",
             "-c",
             "opt",
             f"--repo_env=PYTHON_BIN_PATH={sys.executable}",
+            f"--repo_env=PYTHONPATH={pythonpath}",
         ]
-        if "PYTHONPATH" in os.environ:
-            bazel_args.append(f"--repo_env=PYTHONPATH={os.environ['PYTHONPATH']}")
 
         bazel_args.extend(self._additional_build_options)
         bazel_args.append("//tensorflow_data_validation:move_generated_files")