Speed up spec/tasks/gitlab/git_rake_spec.rb

Because no Git repository was actually created at the temporary path we
were using, `git fsck` would traverse up until it found a repository,
which in our case was the CE or EE repository.

spec/tasks/gitlab/git_rake_spec.rb

 require 'rake_helper'
 
 describe 'gitlab:git rake tasks' do
+  let(:base_path) { 'tmp/tests/default_storage' }
+
   before(:all) do
     @default_storage_hash = Gitlab.config.repositories.storages.default.to_h
   end
 
   before do
     Rake.application.rake_require 'tasks/gitlab/git'
-    storages = { 'default' => Gitlab::GitalyClient::StorageSettings.new(@default_storage_hash.merge('path' => 'tmp/tests/default_storage')) }
+    storages = { 'default' => Gitlab::GitalyClient::StorageSettings.new(@default_storage_hash.merge('path' => base_path)) }
+
+    path = Settings.absolute("#{base_path}/@hashed/1/2/test.git")
+    FileUtils.mkdir_p(path)
+    Gitlab::Popen.popen(%W[git -C #{path} init --bare])
 
-    FileUtils.mkdir_p(Settings.absolute('tmp/tests/default_storage/@hashed/1/2/test.git'))
     allow(Gitlab.config.repositories).to receive(:storages).and_return(storages)
     allow_any_instance_of(String).to receive(:color) { |string, _color| string }
 
@@ -17,7 +22,7 @@ describe 'gitlab:git rake tasks' do
   end
 
   after do
-    FileUtils.rm_rf(Settings.absolute('tmp/tests/default_storage'))
+    FileUtils.rm_rf(Settings.absolute(base_path))
   end
 
   describe 'fsck' do
@@ -26,14 +31,14 @@ describe 'gitlab:git rake tasks' do
     end
 
     it 'errors out about config.lock issues' do
-      FileUtils.touch(Settings.absolute('tmp/tests/default_storage/@hashed/1/2/test.git/config.lock'))
+      FileUtils.touch(Settings.absolute("#{base_path}/@hashed/1/2/test.git/config.lock"))
 
       expect { run_rake_task('gitlab:git:fsck') }.to output(/file exists\? ... yes/).to_stdout
     end
 
     it 'errors out about ref lock issues' do
-      FileUtils.mkdir_p(Settings.absolute('tmp/tests/default_storage/@hashed/1/2/test.git/refs/heads'))
-      FileUtils.touch(Settings.absolute('tmp/tests/default_storage/@hashed/1/2/test.git/refs/heads/blah.lock'))
+      FileUtils.mkdir_p(Settings.absolute("#{base_path}/@hashed/1/2/test.git/refs/heads"))
+      FileUtils.touch(Settings.absolute("#{base_path}/@hashed/1/2/test.git/refs/heads/blah.lock"))
 
       expect { run_rake_task('gitlab:git:fsck') }.to output(/Ref lock files exist:/).to_stdout
     end