GNU sed upstream has requested that the attached patch from the OpenI18N people be applied to sarge. I told him that I would ask the release team.
diff -uprN sed-4.1.1.orig/sed/compile.c sed-4.1.1/sed/compile.c --- sed-4.1.1.orig/sed/compile.c 2004-08-18 20:29:58.742844320 +0900 +++ sed-4.1.1/sed/compile.c 2004-08-18 20:32:53.064343424 +0900 @@ -1309,6 +1309,7 @@ compile_program(vector) memset(&cur_stat, 0, sizeof(mbstate_t)); idx = 0; + len = dest_len; /* trans_pairs = {src(0), dest(0), src(1), dest(1), ..., NULL} src(i) : pointer to i-th source character.