Backup wiki repo even if the main repo is empty

This fixes a bug where wiki repositories for projects with an empty main
repository would not get backed up.

CHANGELOG

@@ -11,6 +11,7 @@ v 6.9.0
   - Improve issue and merge request mobile UI (Drew Blessing)
   - Document how to convert a backup to PostgreSQL
   - Fix locale bug in backup manager
+  - Fix wiki backup skip bug
 v 6.8.0
   - Ability to at mention users that are participating in issue and merge req. discussion

lib/backup/repository.rb

@@ -10,15 +10,12 @@ module Backup
       Project.find_each(batch_size: 1000) do |project|
         print " * #{project.path_with_namespace} ... "
-        if project.empty_repo?
-          puts "[SKIPPED]".cyan
-          next
-        end
-
         # Create namespace dir if missing
         FileUtils.mkdir_p(File.join(backup_repos_path, project.namespace.path)) if project.namespace
-        if system(*%W(git --git-dir=#{path_to_repo(project)} bundle create #{path_to_bundle(project)} --all), silent)
+        if project.empty_repo?
+          puts "[SKIPPED]".cyan
+        elsif system(*%W(git --git-dir=#{path_to_repo(project)} bundle create #{path_to_bundle(project)} --all), silent)
           puts "[DONE]".green
         else
           puts "[FAILED]".red