When debug==1, start fast-import with "--stats" instead of "--quiet"

fast-import prints statistics that could be interesting to the
developer of remote helpers.

Signed-off-by: Florian Achleitner <florian.achleitner.2.6.31@gmail.com>
Acked-by: David Michael Barr <b@rr-dav.id.au>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

transport-helper.c

@@ -385,7 +385,7 @@ static int get_importer(struct transport *transport, struct child_process *fasti
 	memset(fastimport, 0, sizeof(*fastimport));
 	fastimport->in = helper->out;
 	argv_array_push(&argv, "fast-import");
-	argv_array_push(&argv, "--quiet");
+	argv_array_push(&argv, debug ? "--stats" : "--quiet");
 
 	if (data->bidi_import) {
 		cat_blob_fd = xdup(helper->in);