Science dialog not refreshed when getting a tech from a hut

[lmoureaux]

Describe the bug
When getting at tech from a hut, the science dialog and the top bar are not refreshed properly

To Reproduce
Steps to reproduce the behavior:

1. Load hut-bug.tar.gz
2. Take Goyaalé
3. Use the knight to enter the hut at 74,113 (in Japanese territory)
4. You get Leadership for free
5. Check the science report

Expected behavior
The science shows that you got Leadership

Screenshots

Platform and version (please complete the following information):

• OS: Linux
• Freeciv21 version: 7d1b0fc
• Ruleset/Longturn game (if applicable): classic

Additional context
Add any other context about the problem here.

[blabber]

Entering the hut yields a random result. Apply this patch to make sure that you get the tech on entering the hut:

diff --git a/data/default/default.lua b/data/default/default.lua
index f5cfc7f433..0e0532de82 100644
--- a/data/default/default.lua
+++ b/data/default/default.lua
@@ -126,30 +126,7 @@ end
 
 -- Randomly choose a hut event
 function _deflua_hut_enter_callback(unit)
-  local chance = random(0, 11)
-  local alive = true
-
-  if chance == 0 then
-    _deflua_hut_get_gold(unit, 25)
-  elseif chance == 1 or chance == 2 or chance == 3 then
-    _deflua_hut_get_gold(unit, 50)
-  elseif chance == 4 then
-    _deflua_hut_get_gold(unit, 100)
-  elseif chance == 5 or chance == 6 or chance == 7 then
-    _deflua_hut_get_tech(unit)
-  elseif chance == 8 or chance == 9 then
-    if not _deflua_hut_get_mercenaries(unit) then
-      _deflua_hut_consolation_prize(unit)
-    end
-  elseif chance == 10 then
-    alive = _deflua_hut_get_barbarians(unit)
-  elseif chance == 11 then
-    if not _deflua_hut_get_city(unit) then
-      _deflua_hut_consolation_prize(unit)
-    end
-  end
-
-  -- continue processing if unit is alive
+   _deflua_hut_get_tech(unit)
   return (not alive)
 end
 

[blabber]

Just a note: I suspected that this was another regression introduced by 24e44b9, but according to my tests this isn't true.

[lmoureaux]

Oh, we may need to override the Lua random to make this reproducible.

In my test it was also happening with techs from treaties, which is easier to test.

[blabber]

This reproducible in v3.0-patch.4 too.

[lmoureaux]

The server sends an update with Leadership completed and the current research still set to Leadership. It should be A_UNSET instead.