! Unable to load application: NameError: undefined local variable or method `acts_as_positioned' for class RepositoryProtectedBranche

[tomhub]

I was getting this error:
! Unable to load application: NameError: undefined local variable or method acts_as_positioned' for class RepositoryProtectedBranche`

But adding gem 'acts_as_positioned' into Gemfile and bundle update fixed the issue.