Inhibit minecart pickup after detaching driver

When a minecart drives over an activator rail, it detaches its driver.
In cases where the “driver” is a mob or a boat, the mob or boat can get
picked up again immediately, which is likely to be unintended behaviour.

By inhibiting minecart pickup for a second when detaching a mob or boat
from a minecart, activator rails behave as expected: Minecart drivers
are detached and not picked up immediately if they are a mob or boat.

mods/ENTITIES/mcl_minecarts/init.lua

@@ -13,6 +13,7 @@ local function detach_driver(self)
 		return
 	end
 	if not self._driver:is_player() then
+		self._pickup_inhibit_timer = 1
 		self._driver:set_detach()
 		self._driver = nil
 		return
@@ -81,6 +82,7 @@ local function register_entity(entity_id, mesh, textures, drop, on_rightclick, o
 		_old_pos = nil,
 		_old_vel = {x=0, y=0, z=0},
 		_old_switch = 0,
+		_pickup_inhibit_timer = 0, -- how many seconds are mobs and boats not picked up after detaching?
 		_railtype = nil,
 	}
 
@@ -181,8 +183,12 @@ local function register_entity(entity_id, mesh, textures, drop, on_rightclick, o
 	cart.on_activate_by_rail = on_activate_by_rail
 
 	function cart:on_step(dtime)
+		if self._pickup_inhibit_timer > 0 then
+			self._pickup_inhibit_timer = self._pickup_inhibit_timer - dtime
+		end
+
 		local entity_name = self.object:get_luaentity().name
-		if entity_name == "mcl_minecarts:minecart" then
+		if entity_name == "mcl_minecarts:minecart" and self._pickup_inhibit_timer <= 0 then
 			for _, obj in ipairs(minetest.get_objects_inside_radius(self.object:get_pos(), 1.3)) do
 				local entity = obj:get_luaentity()
 				if not self._driver and entity and ( entity._cmi_is_mob or entity.name == "mcl_boats:boat" ) and not obj:get_attach() then