Write Config is mandatory

Closes https://gitlab.com/gitlab-org/gitaly/issues/879

lib/gitlab/git/repository.rb

@@ -1268,16 +1268,10 @@ module Gitlab
         return unless full_path.present?
 
         # This guard avoids Gitaly log/error spam
-        unless exists?
-          raise NoRepository, 'repository does not exist'
-        end
+        raise NoRepository, 'repository does not exist' unless exists?
 
-        gitaly_migrate(:write_config) do |is_enabled|
-          if is_enabled
+        wrapped_gitaly_errors do
           gitaly_repository_client.write_config(full_path: full_path)
-          else
-            rugged_write_config(full_path: full_path)
-          end
         end
       end
 

spec/lib/gitlab/git/repository_spec.rb

@@ -1871,7 +1871,6 @@ describe Gitlab::Git::Repository, seed_helper: true do
       repository_rugged.config["gitlab.fullpath"] = repository_path
     end
 
-    shared_examples 'writing repo config' do
     context 'is given a path' do
       it 'writes it to disk' do
         repository.write_config(full_path: "not-the/real-path.git")
@@ -1907,15 +1906,6 @@ describe Gitlab::Git::Repository, seed_helper: true do
     end
   end
 
-    context "when gitaly_write_config is enabled" do
-      it_behaves_like "writing repo config"
-    end
-
-    context "when gitaly_write_config is disabled", :disable_gitaly do
-      it_behaves_like "writing repo config"
-    end
-  end
-
   describe '#merge' do
     let(:repository) do
       Gitlab::Git::Repository.new('default', TEST_MUTABLE_REPO_PATH, '')