Another gcc -Wall warning squashed:

MPZ_divm():  Initialize mpzden to NULL, since it could be Py_XDECREF()ed
             without being initialized.
diff --git a/Modules/mpzmodule.c b/Modules/mpzmodule.c
index 44349e9..2cce2cc 100644
--- a/Modules/mpzmodule.c
+++ b/Modules/mpzmodule.c
@@ -1209,7 +1209,7 @@
 MPZ_divm(PyObject *self, PyObject *args)
 {
 	PyObject *num, *den, *mod;
-	mpzobject *mpznum, *mpzden, *mpzmod = NULL;
+	mpzobject *mpznum, *mpzden = NULL, *mpzmod = NULL;
 	mpzobject *z = NULL;