sparse-checkout: use default patterns for 'set' only !stdin

"git sparse-checkout set ---no-cone" uses default patterns when none
is given from the command line, but it should do so ONLY when
--stdin is not being used.  Right now, add_patterns_from_input()
called when reading from the standard input is sloppy and does not
check if there are extra command line parameters that the command
will silently ignore, but that will change soon and not setting this
unnecessary and unused default patterns start to matter when it gets
fixed.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: gitster

builtin/sparse-checkout.c

@@ -835,7 +835,7 @@ static int sparse_checkout_set(int argc, const char **argv, const char *prefix)
 	 * non-cone mode, if nothing is specified, manually select just the
 	 * top-level directory (much as 'init' would do).
 	 */
-	if (!core_sparse_checkout_cone && argc == 0) {
+	if (!core_sparse_checkout_cone && !set_opts.use_stdin && argc == 0) {
 		argv = default_patterns;
 		argc = default_patterns_nr;
 	} else {