Explicitly pass PYTHONPATH and python path environs to repository_ctx.execute subprocess in _raw_exec

Author: vkarampudi

third_party/python_configure.bzl

@@ -205,7 +205,11 @@ def _raw_exec(repository_ctx, cmdline):
     Returns:
       The 'exec_result' of repository_ctx.execute().
     """
-    return repository_ctx.execute(cmdline)
+    env = {}
+    for k in ["PYTHONPATH", "PYTHON_BIN_PATH", "PYTHON_LIB_PATH"]:
+        if k in repository_ctx.os.environ:
+            env[k] = repository_ctx.os.environ[k]
+    return repository_ctx.execute(cmdline, environment = env)
 
 def _read_dir(repository_ctx, src_dir):
     """Returns a sorted list with all files in a directory.