Fix subtle bug detected by Jim F.

diff --git a/Objects/abstract.c b/Objects/abstract.c
index e0483a1b83813371a2f837a107f35cb650db0984..382b1fe8a4e8127d2cadd09b31d771c6e36ee5cc 100644 (file)
--- a/Objects/abstract.c
+++ b/Objects/abstract.c
@@ -1032,7 +1032,7 @@ PyObject_CallMethod(va_alist) va_dcl
       return 0;
     }
 
-  if(format)
+  if(format && *format)
     args = Py_VaBuildValue(format, va);
   else
     args = PyTuple_New(0);