background: prevent 404/file not found when no background is selected for an article/rubrique
Merge commit '59e5cf1cdea09d6355cb73d8c487c32067bd591c'

* commit '59e5cf1cdea09d6355cb73d8c487c32067bd591c':
  background: prevent 404/file not found when no background is selected for an article/rubrique