From a59406abdfd1393db708b379003fe3ab0dd0af2e Mon Sep 17 00:00:00 2001
From: Guido van Rossum <guido@python.org>
Date: Fri, 10 Oct 1997 17:39:19 +0000
Subject: Darn.  When thread support is disabled, the BEGIN/END macros don't
 save and restore the tstate, but explicitly calling PyEval_SaveThread() does
 reset it!  While I think about how to fix this for real, here's a fix that
 avoids getting a fatal error.

---
 Modules/_tkinter.c | 9 +++++----
 Modules/readline.c | 3 +++
 2 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/Modules/_tkinter.c b/Modules/_tkinter.c
index 593b057..5958716 100644
--- a/Modules/_tkinter.c
+++ b/Modules/_tkinter.c
@@ -1456,14 +1456,15 @@ static PyInterpreterState *event_interp = NULL;
 static int
 EventHook()
 {
-	PyThreadState *tstate;
+	PyThreadState *tstate, *save_tstate;
 
 	if (Tk_GetNumMainWindows() == 0)
 		return 0;
 	if (event_interp == NULL)
 		return 0;
 	tstate = PyThreadState_New(event_interp);
-	PyEval_AcquireThread(tstate);
+	save_tstate = PyThreadState_Swap(NULL);
+	PyEval_RestoreThread(tstate);
 	if (!errorInCmd)
 		Tcl_DoOneEvent(TCL_DONT_WAIT);
 	if (errorInCmd) {
@@ -1473,7 +1474,8 @@ EventHook()
 		PyErr_Print();
 	}
 	PyThreadState_Clear(tstate);
-	PyEval_ReleaseThread(tstate);
+	PyEval_SaveThread();
+	PyThreadState_Swap(save_tstate);
 	PyThreadState_Delete(tstate);
 	return 0;
 }
@@ -1536,7 +1538,6 @@ init_tkinter()
 	PyDict_SetItemString(d, "TkttType", (PyObject *)&Tktt_Type);
 
 	if (PyOS_InputHook == NULL) {
-		PyEval_InitThreads();
 		event_interp = PyThreadState_Get()->interp;
 		PyOS_InputHook = EventHook;
 	}
diff --git a/Modules/readline.c b/Modules/readline.c
index 1231e03..e12ae1d 100644
--- a/Modules/readline.c
+++ b/Modules/readline.c
@@ -168,8 +168,10 @@ on_completion(text, state)
 	char *result = NULL;
 	if (completer != NULL) {
 		PyObject *r;
+		PyThreadState *save_tstate;
 		/* Note that readline is called with the interpreter
 		   lock released! */
+		save_tstate = PyThreadState_Swap(NULL);
 		PyEval_RestoreThread(tstate);
 		r = PyObject_CallFunction(completer, "si", text, state);
 		if (r == NULL)
@@ -190,6 +192,7 @@ on_completion(text, state)
 		Py_XDECREF(r);
 	  done:
 		PyEval_SaveThread();
+		PyThreadState_Swap(save_tstate);
 	}
 	return result;
 }
-- 
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