show migrated from when loading packages from API

This changes slightly how we load packaged migrated to core taps
when they are loaded using the API. Now it should show the warning
that the package has been migrated and renamed.

Library/Homebrew/cask/cask_loader.rb

@@ -269,14 +269,13 @@ def self.try_new(ref, warn: false)
         return if Homebrew::EnvConfig.no_install_from_api?
         return unless ref.is_a?(String)
 
-        token = parse_token(ref)
-        token ||= begin
-          ref = CoreCaskTap.instance.tap_migration_renames[ref]
-          parse_token(ref) if ref
+        ref = if (token = parse_token(ref))
+          "#{CoreCaskTap.instance}/#{token}"
+        else
+          CoreCaskTap.instance.tap_migration_oldnames_to_full_names[ref]
         end
-        return unless token
 
-        ref = "#{CoreCaskTap.instance}/#{token}"
+        return unless ref
 
         token, tap, = CaskLoader.tap_cask_token_type(ref, warn:)
         new("#{tap}/#{token}")

Library/Homebrew/formulary.rb

@@ -918,23 +918,23 @@ def self.try_new(ref, from: T.unsafe(nil), warn: false)
       return if Homebrew::EnvConfig.no_install_from_api?
       return unless ref.is_a?(String)
 
-      name = parse_name(ref)
-      name ||= begin
-        ref = CoreTap.instance.tap_migration_renames[ref]
-        parse_name(ref) if ref
+      ref = if (name = parse_name(ref))
+        "#{CoreTap.instance}/#{name}"
+      else
+        name = ref.split("/").last
+        CoreTap.instance.tap_migration_oldnames_to_full_names[ref]
       end
-      return unless name
 
-      alias_name = name
+      return unless ref
 
-      ref = "#{CoreTap.instance}/#{name}"
+      alias_name = name
 
       return unless (name_tap_type = Formulary.tap_formula_name_type(ref, warn:))
 
       name, tap, type = name_tap_type
 
       options = if type == :alias
-        { alias_name: alias_name.downcase }
+        { alias_name: T.must(alias_name).downcase }
       else
         {}
       end

Library/Homebrew/tap.rb

@@ -236,7 +236,7 @@ def clear_cache
     @command_files = nil
 
     @tap_migrations = nil
-    @tap_migration_renames = nil
+    @tap_migration_oldnames_to_full_names = nil
     @reverse_tap_migrations_renames = nil
 
     @audit_exceptions = nil
@@ -1285,15 +1285,16 @@ def tap_migrations
     end
   end
 
-  # External formula names to core formula renames
+  # Old formula names (that were migrated to homebrew/core) to old full names.
   sig { returns(T::Hash[String, String]) }
-  def tap_migration_renames
-    @tap_migration_renames ||= Tap.each_with_object({}) do |tap, hash|
+  def tap_migration_oldnames_to_full_names
+    @tap_migration_oldnames_to_full_names ||= Tap.each_with_object({}) do |tap, hash|
       tap.tap_migrations.each do |old_name, new_name|
         next unless new_name.start_with?("homebrew/core/")
 
-        hash[old_name] = new_name
-        hash["#{tap}/#{old_name}"] = new_name
+        full_name = "#{tap}/#{old_name}"
+        hash[old_name] = full_name
+        hash[full_name] = full_name
       end
     end
   end
@@ -1470,15 +1471,16 @@ def tap_migrations
     end
   end
 
-  # External cask names to core cask renames
+  # Old cask names (that were migrated to homebrew/cask) to old full names.
   sig { returns(T::Hash[String, String]) }
-  def tap_migration_renames
-    @tap_migration_renames ||= Tap.each_with_object({}) do |tap, hash|
+  def tap_migration_oldnames_to_full_names
+    @tap_migration_oldnames_to_full_names ||= Tap.each_with_object({}) do |tap, hash|
       tap.tap_migrations.each do |old_name, new_name|
         next unless new_name.start_with?("homebrew/cask/")
 
-        hash[old_name] = new_name
-        hash["#{tap}/#{old_name}"] = new_name
+        full_name = "#{tap}/#{old_name}"
+        hash[old_name] = full_name
+        hash[full_name] = full_name
       end
     end
   end

Library/Homebrew/test/tap_spec.rb

@@ -567,7 +567,7 @@ def setup_completion(link:)
         JSON
       end
 
-      describe "#reverse_tap_migration_renames" do
+      describe "#reverse_tap_migrations_renames" do
         it "returns the expected hash" do
           expect(homebrew_foo_tap.reverse_tap_migrations_renames).to eq({
             "homebrew/cask/google-cloud-sdk" => %w[app-engine-go-32 app-engine-go-64],