BUG/MEDIUM: lua: reset lua transaction between http requests

Previously LUA code would maintain the transaction state between http
requests, resulting in things like txn:get_priv() retrieving data from
a previous request. This addresses the issue by ensuring the LUA state
is reset between requests.

Co-authored-by: Tim Düsterhus <tim@bastelstu.be>
diff --git a/reg-tests/lua/h00001.lua b/reg-tests/lua/h00001.lua
new file mode 100644
index 0000000..999ea88
--- /dev/null
+++ b/reg-tests/lua/h00001.lua
@@ -0,0 +1,15 @@
+core.register_action("bug", { "http-res" }, function(txn)
+	data = txn:get_priv()
+	if not data then
+		data = 0
+	end
+	data = data + 1
+	print(string.format("set to %d", data))
+	txn.http:res_set_status(200 + data)
+	txn:set_priv(data)
+end)
+
+core.register_service("fakeserv", "http", function(applet)
+	applet:set_status(200)
+	applet:start_response()
+end)