fix feature flag for_branch endpoint

lib/travis/api/v3/services/cron/for_branch.rb

@@ -2,7 +2,9 @@ module Travis::API::V3
   class Services::Cron::ForBranch < Service
 
     def run!
-      query.find_for_branch(find(:branch, find(:repository)))
+      repo = find(:repository)
+      raise InsufficientAccess unless Travis::Features.owner_active?(:cron, repo.owner)
+      query.find_for_branch(find(:branch, repo))
     end
   end
 end

spec/v3/services/cron/for_branch_spec.rb

@@ -11,13 +11,13 @@ describe Travis::API::V3::Services::Cron::ForBranch do
   end
 
   describe "find cron job for branch with feature disabled" do
+    before     { cron }
     before     { Travis::Features.deactivate_owner(:cron, repo.owner)   }
     before     { get("/v3/repo/#{repo.id}/branch/#{branch.name}/cron")   }
     example { expect(parsed_body).to be == {
       "@type"         => "error",
-      "error_type"    => "not_found",
-      "error_message" => "cron not found (or insufficient access)",
-      "resource_type" => "cron"
+      "error_type"    => "insufficient_access",
+      "error_message" => "forbidden"
     }}
   end