Eh, better error message for the previous change. It now says

gvanrossum · gvanrossum · commit dfede31c7f52 · 1998-10-02T14:06:56.000Z
"non-default argument follows default argument".
diff --git a/Python/compile.c b/Python/compile.c
@@ -2724,7 +2724,7 @@ com_argdefs(c, n)
 			/* Treat "(a=1, b)" as an error */
 			if (ndefs)
 				com_error(c, PyExc_SyntaxError,
-					  "Missing parameter default value");
+			    "non-default argument follows default argument");
 		}
 		if (t != COMMA)
 			break;

Original file line number	Diff line number	Diff line change
`@@ -2724,7 +2724,7 @@ com_argdefs(c, n)`
`2724`	`2724`	`/* Treat "(a=1, b)" as an error */`
`2725`	`2725`	`if (ndefs)`
`2726`	`2726`	`com_error(c, PyExc_SyntaxError,`
`2727`		`- "Missing parameter default value");`
	`2727`	`+ "non-default argument follows default argument");`
`2728`	`2728`	`}`
`2729`	`2729`	`if (t != COMMA)`
`2730`	`2730`	`break;`