imapc: Fix assert-crash if syncing adds delayed expunges, but fails a…

…fterwards

Fixes:
Panic: file imapc-sync.c: line 328 (imapc_initial_sync_check): assertion failed: (mail_index_is_expunged(view, lseq) || seq_range_exists(&ctx->mbox->delayed_expunged_uids, luid))

src/lib-storage/index/imapc/imapc-sync.c

@@ -496,13 +496,13 @@ static int imapc_sync_finish(struct imapc_sync_context **_ctx)
 	int ret = ctx->failed ? -1 : 0;
 
 	*_ctx = NULL;
-	if (ret == 0) {
-		if (mail_index_sync_commit(&ctx->index_sync_ctx) < 0) {
-			mailbox_set_index_error(&ctx->mbox->box);
-			ret = -1;
-		}
-	} else {
-		mail_index_sync_rollback(&ctx->index_sync_ctx);
+	/* Commit the transaction even if we failed. This is important, because
+	   during the sync delayed_sync_trans points to the sync transaction.
+	   Even if the syncing doesn't fully succeed, we don't want to lose
+	   changes in delayed_sync_trans. */
+	if (mail_index_sync_commit(&ctx->index_sync_ctx) < 0) {
+		mailbox_set_index_error(&ctx->mbox->box);
+		ret = -1;
 	}
 	if (ctx->mbox->sync_gmail_pop3_search_tag != NULL) {
 		mailbox_set_critical(&ctx->mbox->box,