Issue #9448: Fix a leak of OS resources (mutexes or semaphores) when
re-initializing a buffered IO object by calling its `__init__` method.
diff --git a/Modules/_io/bufferedio.c b/Modules/_io/bufferedio.c
index 07fe0a1..1dd1ec4 100644
--- a/Modules/_io/bufferedio.c
+++ b/Modules/_io/bufferedio.c
@@ -636,6 +636,8 @@
         return -1;
     }
 #ifdef WITH_THREAD
+    if (self->lock)
+        PyThread_free_lock(self->lock);
     self->lock = PyThread_allocate_lock();
     if (self->lock == NULL) {
         PyErr_SetString(PyExc_RuntimeError, "can't allocate read lock");