Wander spawns code meant to exclude monsters on other z-levels does not work

[chaosvolt]

Describe the bug

So I was made aware of another case of a monster in a basement level possibly escaping containment due to wandering hordes behavior.

Then I remembered #4205 and realized, that shoudn't have happened in the first place: https://github.com/cataclysmbnteam/Cataclysm-BN/blob/main/src/overmap.cpp#L3735

            // Only zombies on z-level 0 may join hordes.
            if( p.z() != 0 ) {
                monster_map_it++;
                continue;
            }

This doesn't seem to be working, seeing as I encountered a trapped tendril out in the lake that first time when it spawns on z-level minus 1, and likewise someone in the discord reported a dracolich from Arcana mod having escaped containment via some means (either wandering hordes behavior, or if not that then 3D vision not playing well with flying monsters again).

Steps To Reproduce

1. Find some location with a zombie-type monster that can only typically be found safely locked up underground.
2. Fuck about with hordes mode on.
3. Potentially, if all goes well, encounter the creature someplace later on topside, despite having never allowed the creature to escape.

Screenshots

No response

Versions and configuration

• OS: Windows
  • OS Version: 10.0.19041.450 (2004)
• Game Version: ecb842b [64-bit]
• Graphics Version: Tiles
• LAPI Version: 2
• Game Language: []
• Mods loaded: [
  Bright Nights [bn],
  Arcana and Magic Items [Arcana],
  Cataclysm++ [Cata++],
  Medieval Mod Reborn [Medieval_Mod_Reborn],
  MST Extra [MST_Extra],
  Arcana/Cata++ Patchmod [Arcana_Cata++_Patch],
  Mining Mod [Mining_Mod],
  Tankmod: Revived [Tankmod_Revived],
  No Fungal Monsters [No_Fungi],
  Disable NPC Needs [no_npc_food],
  Faster Stamina Regen [stamina_regen_buff],
  Manual Bionic Installation [manualbionicinstall],
  Simplified Nutrition [novitamins],
  Stats Through Kills [stats_through_kills],
  SpeedyDex [speedydex],
  Stats Through Skills [StatsThroughSkills]
  ]

Additional context

No response

[Soadreqm]

Trapped tendrils spawn at ground level though, don't they?

[chaosvolt]

Oh wait, you're right, it's the flesh wall that spawns in the basement. In that case I need to test the dracolich more since that was the other monster reported to have wandered up to the surface, as mentioned in the discord. I dunno what else might be able to escape nor how to easily narrow down the potential cause...