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
-        gitaly_migrate(:write_config) do |is_enabled|
-          if is_enabled
-            gitaly_repository_client.write_config(full_path: full_path)
-          else
-            rugged_write_config(full_path: full_path)
-          end
+        raise NoRepository, 'repository does not exist' unless exists?
+        wrapped_gitaly_errors do
+          gitaly_repository_client.write_config(full_path: full_path)
         end
       end

spec/lib/gitlab/git/repository_spec.rb

@@ -1871,49 +1871,39 @@ 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")
-          config = File.read(File.join(repository_path, "config"))
-          expect(config).to include("[gitlab]")
-          expect(config).to include("fullpath = not-the/real-path.git")
-        end
+    context 'is given a path' do
+      it 'writes it to disk' do
+        repository.write_config(full_path: "not-the/real-path.git")
+        config = File.read(File.join(repository_path, "config"))
+        expect(config).to include("[gitlab]")
+        expect(config).to include("fullpath = not-the/real-path.git")
       end
-      context 'it is given an empty path' do
-        it 'does not write it to disk' do
-          repository.write_config(full_path: "")
-          config = File.read(File.join(repository_path, "config"))
-          expect(config).to include("[gitlab]")
-          expect(config).to include("fullpath = #{repository_path}")
-        end
+    end
+    context 'it is given an empty path' do
+      it 'does not write it to disk' do
+        repository.write_config(full_path: "")
+        config = File.read(File.join(repository_path, "config"))
+        expect(config).to include("[gitlab]")
+        expect(config).to include("fullpath = #{repository_path}")
       end
-      context 'repository does not exist' do
-        it 'raises NoRepository and does not call Gitaly WriteConfig' do
-          repository = Gitlab::Git::Repository.new('default', 'does/not/exist.git', '')
-          expect(repository.gitaly_repository_client).not_to receive(:write_config)
-          expect do
-            repository.write_config(full_path: 'foo/bar.git')
-          end.to raise_error(Gitlab::Git::Repository::NoRepository)
-        end
+    end
+    context 'repository does not exist' do
+      it 'raises NoRepository and does not call Gitaly WriteConfig' do
+        repository = Gitlab::Git::Repository.new('default', 'does/not/exist.git', '')
+        expect(repository.gitaly_repository_client).not_to receive(:write_config)
+        expect do
+          repository.write_config(full_path: 'foo/bar.git')
+        end.to raise_error(Gitlab::Git::Repository::NoRepository)
       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