Fix a bug where the tgz returned got encoded utf8

Conflicts:
	doc/api/repositories.md

Change-Id: I7ebc39b47ff860813d9622ba6776583536e6e384

doc/api/repositories.md

@@ -368,4 +368,4 @@ GET /projects/:id/repository/archive
 
 Parameters:
 + `id` (required) - The ID of a project
-+ `sha` (optional) - The commit or branch name
++ `sha` (optional) - The commit sha to download defaults to the tip of the default branch

lib/api/repositories.rb

@@ -181,7 +181,7 @@ module API
       #
       # Parameters:
       #   id (required) - The ID of a project
-      #   sha (optional) - the commit sha to download defaults to head
+      #   sha (optional) - the commit sha to download defaults to the tip of the default branch
       # Example Request:
       #   GET /projects/:id/repository/archive
       get ":id/repository/archive" do
@@ -190,11 +190,15 @@ module API
         ref = params[:sha]
         storage_path = Rails.root.join("tmp", "repositories")
 
-        file_path = repo.archive_repo(ref || 'HEAD', storage_path)
-        if file_path
-          data = File.open(file_path).read
-          content_type 'application/x-gzip'
+        file_path = repo.archive_repo(ref, storage_path)
+        if file_path && File.exists?(file_path)
+          data = File.open(file_path, 'rb').read
+
           header "Content-Disposition:", " infile; filename=\"#{File.basename(file_path)}\""
+          content_type 'application/x-gzip'
+
+          env['api.format'] = :binary
+
           present data
         else
           not_found!