Refactor empty? to call only Gitaly endpoints

Needed for the Gitaly migration, see
https://gitlab.com/gitlab-org/gitaly/issues/699

lib/gitlab/git/repository.rb

@@ -76,9 +76,6 @@ module Gitlab
         @attributes = Gitlab::Git::Attributes.new(path)
       end
 
-      delegate  :empty?,
-                to: :rugged
-
       def ==(other)
         path == other.path
       end
@@ -197,6 +194,10 @@ module Gitlab
         end
       end
 
+      def empty?
+        !exists? || !has_local_branches?
+      end
+
       def has_local_branches?
         gitaly_migrate(:has_local_branches) do |is_enabled|
           if is_enabled

lib/gitlab/gitaly_client.rb

@@ -27,7 +27,7 @@ module Gitlab
     end
 
     SERVER_VERSION_FILE = 'GITALY_SERVER_VERSION'.freeze
-    MAXIMUM_GITALY_CALLS = 30
+    MAXIMUM_GITALY_CALLS = 35
     CLIENT_NAME = (Sidekiq.server? ? 'gitlab-sidekiq' : 'gitlab-web').freeze
 
     MUTEX = Mutex.new

spec/lib/gitlab/git/repository_spec.rb

@@ -257,7 +257,7 @@ describe Gitlab::Git::Repository, seed_helper: true do
   end
 
   describe '#empty?' do
-    it { expect(repository.empty?).to be_falsey }
+    it { expect(repository).not_to be_empty }
   end
 
   describe '#ref_names' do