bpo-33128 Fix duplicated call to importlib._install_external_importers (GH-6273)

External importers were being added in both phases of the import
system initialisation.

They're only supposed to be added in the second phase, after the
import machinery has been appropriately configured.

diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 6933b41353bd56386df4d3a955944f6d217afcc9..336ae447a8de5e5aad9c89886cd40a168f3d5200 100644 (file)
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -852,6 +852,9 @@ class SysModuleTest(unittest.TestCase):
         check(-1<<1000, [traceback[-1]])
         check(None, traceback)
 
+    def test_no_duplicates_in_meta_path(self):
+        self.assertEqual(len(sys.meta_path), len(set(sys.meta_path)))
+
 
 @test.support.cpython_only
 class SizeofTest(unittest.TestCase):

diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-04-24-22-31-04.bpo-33128.g2yLuf.rst b/Misc/NEWS.d/next/Core and Builtins/2018-04-24-22-31-04.bpo-33128.g2yLuf.rst
new file mode 100644 (file)
index 0000000..66b98cd
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2018-04-24-22-31-04.bpo-33128.g2yLuf.rst
@@ -0,0 +1,2 @@
+Fix a bug that causes PathFinder to appear twice on sys.meta_path. Patch by
+Pablo Galindo Salgado.

diff --git a/Python/pylifecycle.c b/Python/pylifecycle.c
index a9b9470c726521e2b15b5cddce7a8167d534b24d..958219b744580d451c6f8670b2f847d5c01b3d5c 100644 (file)
--- a/Python/pylifecycle.c
+++ b/Python/pylifecycle.c
@@ -325,11 +325,6 @@ initimport(PyInterpreterState *interp, PyObject *sysmod)
 
     /* Install importlib as the implementation of import */
     value = PyObject_CallMethod(importlib, "_install", "OO", sysmod, impmod);
-    if (value != NULL) {
-        Py_DECREF(value);
-        value = PyObject_CallMethod(importlib,
-                                    "_install_external_importers", "");
-    }
     if (value == NULL) {
         PyErr_Print();
         return _Py_INIT_ERR("importlib install failed");