commit 98d90f745d35d5d07bffcb46788b50e05eea56c6
author Christian Heimes <christian@python.org> Tue Aug 27 23:36:56 2019 +0200
committer GitHub <noreply@github.com> Tue Aug 27 23:36:56 2019 +0200
tree ef3fd981f4f82f06e73b014bc742cf7a5acfebd9
parent 3224e1a6bb23b1b322f5b9424b10ab68c9127dcc

bpo-37951: Lift subprocess's fork() restriction (GH-15544)

Modules/_posixsubprocess.c

diff --git a/Modules/_posixsubprocess.c b/Modules/_posixsubprocess.c
index 60c8eab..f68d362 100644
--- a/Modules/_posixsubprocess.c
+++ b/Modules/_posixsubprocess.c
@@ -583,8 +583,10 @@
             &restore_signals, &call_setsid, &preexec_fn))
         return NULL;
 
-    if (_PyInterpreterState_Get() != PyInterpreterState_Main()) {
-        PyErr_SetString(PyExc_RuntimeError, "fork not supported for subinterpreters");
+    if ((preexec_fn != Py_None) &&
+            (_PyInterpreterState_Get() != PyInterpreterState_Main())) {
+        PyErr_SetString(PyExc_RuntimeError,
+                        "preexec_fn not supported within subinterpreters");
         return NULL;
     }