BUG/MINOR: proto_htx: Truncate the request when an error is detected

When HTTP_MSGF_ERROR is set on a channel (the request or the response), the
request must be truncated, not the response.
diff --git a/src/proto_htx.c b/src/proto_htx.c
index b6c127e..e76d0bf 100644
--- a/src/proto_htx.c
+++ b/src/proto_htx.c
@@ -5220,7 +5220,7 @@
 
 	if (unlikely(txn->req.msg_state == HTTP_MSG_ERROR ||
 		     txn->rsp.msg_state == HTTP_MSG_ERROR)) {
-		channel_truncate(chn);
+		channel_truncate(&s->req);
 		channel_abort(&s->req);
 		goto end;
 	}
@@ -5292,7 +5292,7 @@
 	if (txn->rsp.msg_state == HTTP_MSG_CLOSED) {
 	  http_msg_closed:
 		/* drop any pending data */
-		channel_truncate(chn);
+		channel_truncate(&s->req);
 		channel_abort(&s->req);
 		goto end;
 	}