Supervisor: old child specs remained in CRDT after process handoff

When an existing child spec was added to the CRDT during process
handoff, the old child spec is never removed from the CRDT, creating
lingering child specs which results in "zombie" processes spawning
when a new supervisor is started.

lib/horde/dynamic_supervisor_impl.ex

@@ -422,6 +422,7 @@ defmodule Horde.DynamicSupervisorImpl do
 
               case current_member do
                 %{status: :dead} ->
+                  DeltaCrdt.delete(crdt_name(state.name), {:process, child_spec.id}, :infinity)
                   {_response, state} = add_child(randomize_child_id(child_spec), state)
 
                   state

test/dynamic_supervisor_test.exs

@@ -446,6 +446,18 @@ defmodule DynamicSupervisorTest do
 
       Process.sleep(5000)
       assert_receive {:starting, 5000}, 100
+
+      # we have 2 supervised processes
+      processes = :sys.get_state(:horde_2_graceful).processes_by_id
+      assert Horde.TableUtils.size_of(processes) == 2
+
+      # peek into the remaining supervisor, getting the supervised pids
+      pids =
+        :sys.get_state(:horde_2_graceful).processes_by_id
+        |> :ets.tab2list()
+        |> Enum.map(&(elem(&1, 1) |> elem(2)))
+
+      assert Enum.all?(pids, &Process.alive?/1)
     end
   end