Fix for implicit tuple + default arguments, courtesy of Michael Hudson.
SF patch #103749
diff --git a/Python/compile.c b/Python/compile.c
index bc568c9..f2d424b 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -4667,7 +4667,9 @@
 		for (j = 0; j <= complex; j++) {
 			c = CHILD(n, j);
 			if (TYPE(c) == COMMA)
-			    c = CHILD(n, ++j);
+				c = CHILD(n, ++j);
+			else if (TYPE(c) == EQUAL)
+				c = CHILD(n, j += 3);
 			if (TYPE(CHILD(c, 0)) == LPAR)
 				symtable_params_fplist(st, CHILD(c, 1));
 		}