Erk, I forgot that regress.in has an ending newline, so change the test for

transliterate to use echo -n to supress newline and a simple string.

tools/regression/usr.bin/sed/regress.sh

@@ -5,6 +5,6 @@ REGRESSION_START($1)
 REGRESSION_TEST(`G', `sed G < regress.in')
 REGRESSION_TEST(`P', `sed P < regress.in')
 REGRESSION_TEST(`psl', `sed \$!g\;P\;D < regress.in')
-REGRESSION_TEST(`y', `sed y/\(\)/{}/ < regress.in')
+REGRESSION_TEST(`y', `echo -n foo | sed y/o/O/')
 
 REGRESSION_END()

tools/regression/usr.bin/sed/regress.y.out

@@ -1,4 +1 @@
-input
-data
-for validation
-of sed{1}
+fOo