bpo-38234: Fix PyConfig_Read() when Py_SetPath() was called (GH-16298)

* If Py_SetPath() has been called, _PyConfig_InitPathConfig() now
  uses its value.
* Py_Initialize() now longer copies path configuration from PyConfig
  to the global path configuration (_Py_path_config).

1 files changed, 6 insertions, 4 deletions

diff --git a/Modules/getpath.c b/Modules/getpath.c
index 36f9860..3946623 100644
--- a/Modules/getpath.c
+++ b/Modules/getpath.c
@@ -1213,10 +1213,12 @@ calculate_path_impl(const PyConfig *config,
                 "Consider setting $PYTHONHOME to <prefix>[:<exec_prefix>]\n");
     }
 
-    status = calculate_module_search_path(config, calculate,
-                                       prefix, exec_prefix, pathconfig);
-    if (_PyStatus_EXCEPTION(status)) {
-        return status;
+    if (pathconfig->module_search_path == NULL) {
+        status = calculate_module_search_path(config, calculate,
+                                              prefix, exec_prefix, pathconfig);
+        if (_PyStatus_EXCEPTION(status)) {
+            return status;
+        }
     }
 
     status = calculate_reduce_prefix(calculate, prefix, Py_ARRAY_LENGTH(prefix));