--- a/mercurial/pathencode.c	Tue Aug 18 16:43:26 2015 -0400
+++ b/mercurial/pathencode.c	Tue Aug 18 16:32:41 2015 -0400
@@ -684,6 +684,8 @@
 
 	hashobj = PyObject_CallMethod(shaobj, "digest", "");
 	Py_DECREF(shaobj);
+	if (hashobj == NULL)
+		return -1;
 
 	if (!PyString_Check(hashobj) || PyString_GET_SIZE(hashobj) != 20) {
 		PyErr_SetString(PyExc_TypeError,