discontinued remains of duplicate exception UnequalLengths (cf. 441260986b63);
--- a/src/Pure/library.ML Mon Mar 19 21:10:33 2012 +0100
+++ b/src/Pure/library.ML Mon Mar 19 21:16:19 2012 +0100
@@ -1082,4 +1082,3 @@
structure Basic_Library: BASIC_LIBRARY = Library;
open Basic_Library;
-datatype legacy = UnequalLengths;