Warn if fetching registry without outer checksum

lib/hex/repo.ex

@@ -294,6 +294,15 @@ defmodule Hex.Repo do
     else
       case :mix_hex_registry.decode_package(body, repo, package) do
         {:ok, releases} ->
+          outer_checksum? = Enum.all?(releases, &Map.has_key?(&1, :outer_checksum))
+
+          if not outer_checksum? and Hex.Server.should_warn_registry_version?() do
+            Hex.Shell.warn(
+              "Fetched old registry record version from repo #{repo}. The" <>
+                "repository you are using should update to include the new :outer_checksum field"
+            )
+          end
+
           releases
 
         {:error, :unverified} ->

lib/hex/server.ex

@@ -18,6 +18,10 @@ defmodule Hex.Server do
     GenServer.call(@name, :should_warn_lock_version?)
   end
 
+  def should_warn_registry_version?() do
+    GenServer.call(@name, :should_warn_registry_version?)
+  end
+
   def init([]) do
     {:ok, state()}
   end
@@ -26,15 +30,26 @@ defmodule Hex.Server do
     {:reply, :ok, state()}
   end
 
-  def handle_call(:should_warn_lock_version?, _from, %{warned_tuple_size: false} = state) do
-    {:reply, true, %{state | warned_tuple_size: true}}
+  def handle_call(:should_warn_lock_version?, _from, %{warned_lock_version: false} = state) do
+    {:reply, true, %{state | warned_lock_version: true}}
+  end
+
+  def handle_call(:should_warn_lock_version?, _from, %{warned_lock_version: true} = state) do
+    {:reply, false, state}
+  end
+
+  def handle_call(:should_warn_registry_version?, _from, %{warned_registry_size: false} = state) do
+    {:reply, true, %{state | warned_registry_size: true}}
   end
 
-  def handle_call(:should_warn_lock_version?, _from, %{warned_tuple_size: true} = state) do
+  def handle_call(:should_warn_registry_version?, _from, %{warned_registry_size: true} = state) do
     {:reply, false, state}
   end
 
   defp state() do
-    %{warned_tuple_size: false}
+    %{
+      warned_lock_version: false,
+      warned_registry_version: false
+    }
   end
 end