Fixed control character enconding in jencode

util/jescape.c

@@ -29,8 +29,8 @@ char *jescape(char *s)
 			case '\t':
 				fputs("\\t", stream); break;
 			default:
-				if (*s <= 0x1f)
-					fprintf(stream, "\\u%04x", *s);
+				if (*s <= 0x1f && *s >= 0)
+					fprintf(stream, "\\u%04hhx", *s);
 				else
 					fputc(*s, stream);
 		}