Merge branch 'backport-ee-cache-invalidation-to-ce-ee' into 'master'

EE: Use the same way to invalidate cache from EE

See merge request !2134

app/services/issuable_base_service.rb

@@ -236,11 +236,9 @@ class IssuableBaseService < BaseService
         )
 
         if old_assignees != issuable.assignees
-          ## EE-specific
           new_assignees = issuable.assignees.to_a
           affected_assignees = (old_assignees + new_assignees) - (old_assignees & new_assignees)
           invalidate_cache_counts(affected_assignees.compact, issuable)
-          ## EE-specific
         end
 
         after_update(issuable)