Oh, my god... bc with readline support does not work at all:

echo 10 / 3 | bc
prints
	10 / 3\r\n\r3\r\n
with a stock readline... Our readline does not echo when it does not
have a tty, so it printed:
	\r3\n
I removed printing the printing of \r for now...

gnu/usr.bin/bc/scan.l

@@ -107,7 +107,9 @@ rl_input (buf, result, max)
       if (rl_len != 1)
 	add_history (rl_line); 
       rl_line[rl_len-1] = '\n';
+#if 0
       printf ("\r");
+#endif
       fflush (stdout);
     }