[BUG] stick_table: fix possible memory leak in case of connection error

If a "stick store-request" rule is present, an entry is preallocated during
the request. However, if there is no response due to an error or to a redir
mode server, we never release it.
diff --git a/src/session.c b/src/session.c
index 5229c7f..d5dbff2 100644
--- a/src/session.c
+++ b/src/session.c
@@ -50,6 +50,7 @@
 	struct http_txn *txn = &s->txn;
 	struct proxy *fe = s->fe;
 	struct bref *bref, *back;
+	int i;
 
 	if (s->pend_pos)
 		pendconn_free(s->pend_pos);
@@ -82,6 +83,13 @@
 
 	http_end_txn(s);
 
+	for (i = 0; i < s->store_count; i++) {
+		if (!s->store[i].ts)
+			continue;
+		stksess_free(s->store[i].table, s->store[i].ts);
+		s->store[i].ts = NULL;
+	}
+
 	if (fe) {
 		pool_free2(fe->hdr_idx_pool, txn->hdr_idx.v);
 		pool_free2(fe->rsp_cap_pool, txn->rsp.cap);