Fix for [ 1010677 ] thread Module Breaks PyGILState_Ensure(),

and a test case.
When booting a new thread, use the PyGILState API to manage the GIL.

Lib/test/test_capi.py

@@ -43,3 +43,7 @@ except AttributeError:
 
 if have_thread_state:
     TestThreadState()
+    import threading
+    t=threading.Thread(target=TestThreadState)
+    t.start()
+

Modules/threadmodule.c

@@ -425,11 +425,10 @@ static void
 t_bootstrap(void *boot_raw)
 {
 	struct bootstate *boot = (struct bootstate *) boot_raw;
-	PyThreadState *tstate;
+	PyGILState_STATE gstate;
 	PyObject *res;
 
-	tstate = PyThreadState_New(boot->interp);
-	PyEval_AcquireThread(tstate);
+	gstate = PyGILState_Ensure();
 	res = PyEval_CallObjectWithKeywords(
 		boot->func, boot->args, boot->keyw);
 	if (res == NULL) {
@@ -454,8 +453,7 @@ t_bootstrap(void *boot_raw)
 	Py_DECREF(boot->args);
 	Py_XDECREF(boot->keyw);
 	PyMem_DEL(boot_raw);
-	PyThreadState_Clear(tstate);
-	PyThreadState_DeleteCurrent();
+	PyGILState_Release(gstate);
 	PyThread_exit_thread();
 }