Properly fix wiki restore.

ProjectWiki.new() creates a new wiki git repository, so any tries
to bare clone a bundle fail. With this patch we remove the newly
created wiki.git before restoring from the backup bundle.

Conflicts:
	lib/backup/repository.rb

lib/backup/repository.rb

@@ -55,7 +55,7 @@ module Backup
       FileUtils.mkdir_p(repos_path)
 
       Project.find_each(batch_size: 1000) do |project|
-        print "#{project.path_with_namespace} ... "
+        print " * #{project.path_with_namespace} ... "
 
         project.namespace.ensure_dir_exist if project.namespace
 
@@ -76,10 +76,18 @@ module Backup
 
         if File.exists?(path_to_bundle(wiki))
           print " * #{wiki.path_with_namespace} ... "
-          if system(*%W(git clone --bare #{path_to_bundle(wiki)} #{path_to_repo(wiki)}), silent)
+
+          # If a wiki bundle exists, first remove the empty repo
+          # that was initialized with ProjectWiki.new() and then
+          # try to restore with 'git clone --bare'.
+          FileUtils.rm_rf(path_to_repo(wiki))
+          cmd = %W(git clone --bare #{path_to_bundle(wiki)} #{path_to_repo(wiki)})
+
+          if system(*cmd, silent)
             puts " [DONE]".green
           else
             puts " [FAILED]".red
+            puts "failed: #{cmd.join(' ')}"
             abort 'Restore failed'
           end
         end