Index: Modules/_posixsubprocess.c
===================================================================
--- Modules/_posixsubprocess.c	(révision 80063)
+++ Modules/_posixsubprocess.c	(copie de travail)
@@ -177,6 +177,7 @@
     int p2cread, p2cwrite, c2pread, c2pwrite, errread, errwrite;
     int errpipe_read, errpipe_write, close_fds, restore_signals;
     int call_setsid;
+    PyObject *cwd_obj, *cwd_obj2 = NULL;
     const char *cwd;
     pid_t pid;
     int need_to_reenable_gc = 0;
@@ -184,8 +185,9 @@
     Py_ssize_t arg_num;
 
     if (!PyArg_ParseTuple(
-            args, "OOOzOiiiiiiiiiiO:fork_exec",
-            &process_args, &executable_list, &py_close_fds, &cwd, &env_list,
+            args, "OOOOOiiiiiiiiiiO:fork_exec",
+            &process_args, &executable_list, &py_close_fds,
+            &cwd_obj, &env_list,
             &p2cread, &p2cwrite, &c2pread, &c2pwrite,
             &errread, &errwrite, &errpipe_read, &errpipe_write,
             &restore_signals, &call_setsid, &preexec_fn))
@@ -266,10 +268,20 @@
 	_PyImport_AcquireLock();
     }
 
+    if (cwd_obj != Py_None)
+    {
+        if (PyUnicode_FSConverter(cwd_obj, &cwd_obj2) == 0)
+            goto cleanup;
+        assert(PyBytes_Check(cwd_obj2));
+        cwd = PyBytes_AsString(cwd_obj2);
+    } else {
+        cwd = NULL;
+    }
+
     pid = fork();
     if (pid == 0) {
         /* Child process */
-        /* 
+        /*
          * Code from here to _exit() must only use async-signal-safe functions,
          * listed at `man 7 signal` or
          * http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_04.html.
@@ -291,6 +303,9 @@
         _exit(255);
         return NULL;  /* Dead code to avoid a potential compiler warning. */
     }
+    if (cwd_obj2 != NULL)
+        Py_DECREF(cwd_obj2);
+
     if (pid == -1) {
         /* Capture the errno exception before errno can be clobbered. */
         PyErr_SetFromErrno(PyExc_OSError);