Raise an error if no protocol is passed to the GitAccess check.

lib/gitlab/git/hook.rb

 module Gitlab
   module Git
     class Hook
+      GL_PROTOCOL = 'web'.freeze
       attr_reader :name, :repo_path, :path
 
       def initialize(name, repo_path)
@@ -35,7 +36,7 @@ module Gitlab
         vars = {
           'GL_ID' => gl_id,
           'PWD' => repo_path,
-          'GL_PROTOCOL' => 'web'
+          'GL_PROTOCOL' => GL_PROTOCOL
         }
 
         options = {

lib/gitlab/git_access.rb

@@ -50,7 +50,7 @@ module Gitlab
     end
 
     def check(cmd, changes = nil)
-      return build_status_object(false, 'Access denied due to unspecified Git access protocol') unless protocol
+      raise 'Access denied due to unspecified Git access protocol' unless protocol
 
       return build_status_object(false, "Git access over #{protocol.upcase} is not allowed") unless protocol_allowed?