Index: Modules/threadmodule.c
===================================================================
--- Modules/threadmodule.c	(revision 66050)
+++ Modules/threadmodule.c	(working copy)
@@ -278,7 +278,9 @@
 				return NULL;
 		}
 
-		Py_CLEAR(self->dict);
+		while (self->dict != NULL) {
+			Py_CLEAR(self->dict);
+		}
 		Py_INCREF(ldict);
 		self->dict = ldict; /* still borrowed */
 
@@ -297,7 +299,9 @@
 	/* The call to tp_init above may have caused another thread to run.
 	   Install our ldict again. */
 	if (self->dict != ldict) {
-		Py_CLEAR(self->dict);
+		while (self->dict != NULL) {
+			Py_CLEAR(self->dict);
+		}
 		Py_INCREF(ldict);
 		self->dict = ldict;
 	}