[PATCH v2] fix: release transaction before releasing handle

[Kevin Morris]

If a transaction exists, release it if possible. If
`alpm_trans_release` errors out (returns a non-zero),
return a -1 in `alpm_release`.

This patch addresses the following issue observed in `pyalpm`:
https://gitlab.archlinux.org/archlinux/pyalpm/-/issues/25, where
`pyalpm` ends up raising twice due to an unexpected failure during
handle release, while a transaction is locked.

This is a modified version of
https://patchwork.archlinux.org/project/pacman/patch/20200119191833.581492-1-morganamilo@archlinux.org/
and is a derivation of his (Morganamilo's) work.

Signed-off-by: Kevin Morris <kevr at 0cost.org>
---
 lib/libalpm/alpm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/lib/libalpm/alpm.c b/lib/libalpm/alpm.c
index 6708e202..47d02fea 100644
--- a/lib/libalpm/alpm.c
+++ b/lib/libalpm/alpm.c
@@ -100,6 +100,10 @@ int SYMEXPORT alpm_release(alpm_handle_t *myhandle)
 
 	CHECK_HANDLE(myhandle, return -1);
 
+	if (myhandle->trans != NULL && alpm_trans_release(myhandle)) {
+		return -1;
+	}
+
 	/* close local database */
 	db = myhandle->db_local;
 	if(db) {
-- 
2.34.0