do not try to download an empty db list

Starting the download process, even if there is nothing to actually
download, causes an error when pacman is built without curl and has no
XferCommand defined (like our test suite).

Signed-off-by: Andrew Gregory <andrew.gregory.8@gmail.com>
Signed-off-by: Allan McRae <allan@archlinux.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/lib/libalpm/be_sync.c b/lib/libalpm/be_sync.c
index 0a5cb7c2..91e5f5cf 100644
--- a/lib/libalpm/be_sync.c
+++ b/lib/libalpm/be_sync.c
@@ -198,6 +198,10 @@ int SYMEXPORT alpm_db_update(alpm_handle_t *handle, alpm_list_t *dbs, int force)
 		payload->max_size = 128 * 1024 * 1024;
 		payloads = alpm_list_add(payloads, payload);
 	}
+	if(payloads == NULL) {
+		ret = 0;
+		goto cleanup;
+	}
 
 	event.type = ALPM_EVENT_DB_RETRIEVE_START;
 	EVENT(handle, &event);