Remove direct disk access in RemoveDotGitFromUsernames

Prior to this change, the migration touched the disk path. This has been
removed.

Further, I believe it also fixes a bug. It seems that GitLab Shell
checks if the root path exists, when the path is duplicated. For
example, if the shard is located at /home/git, it did check if
`/home/git/home/git` existed.

db/migrate/20161226122833_remove_dot_git_from_usernames.rb

-# See http://doc.gitlab.com/ce/development/migration_style_guide.html
-# for more information on how to write migrations for GitLab.
-
 class RemoveDotGitFromUsernames < ActiveRecord::Migration
   include Gitlab::Database::MigrationHelpers
   include Gitlab::ShellAdapter
-  # Set this constant to true if this migration requires downtime.
   DOWNTIME = false
   def up
@@ -64,16 +60,14 @@ class RemoveDotGitFromUsernames < ActiveRecord::Migration
     # we rename suffix instead of removing it
     path = path.sub(/\.git\z/, '_git')
-    Gitlab::GitalyClient::StorageSettings.allow_disk_access do
-      check_routes(path.dup, 0, path)
-    end
+    check_routes(path.dup, 0, path)
   end
   def check_routes(base, counter, path)
     route_exists = route_exists?(path)
-    Gitlab.config.repositories.storages.each do |shard, storage|
-      if route_exists || path_exists?(shard, storage.legacy_disk_path)
+    Gitlab.config.repositories.storages.each do |shard, _storage|
+      if route_exists || path_exists?(shard, path)
         counter += 1
         path = "#{base}#{counter}"

spec/migrations/migrate_process_commit_worker_jobs_spec.rb

@@ -27,7 +27,7 @@ describe MigrateProcessCommitWorkerJobs do
     end
     describe '#repository' do
-      it 'returns a Rugged::Repository' do
+      it 'returns a mock implemention of ::Repository' do
         migration_project = described_class::Project
           .find_including_path(project.id)
@@ -83,11 +83,7 @@ describe MigrateProcessCommitWorkerJobs do
     end
     it 'encodes data to UTF-8' do
-      allow_any_instance_of(Rugged::Repository).to receive(:lookup)
-        .with(commit.id)
-        .and_return(commit)
-
-      allow(commit).to receive(:message)
+      allow(commit).to receive(:body)
         .and_return('김치'.force_encoding('BINARY'))
       migration.up