Rudder

Coming from a very old rudder, in rudder 6.1 when we try to create a new user technique, we get an error:

[2020-06-17 14:29:26] ERROR com.normation.rudder.services.policies.TechniqueAcceptationUpdater - Error when trying to create to hierarchy of categories into which the new technique should be added: Consistancy: A category with that name already exists in that category: category names must be unique for a given level
[2020-06-17 14:29:26] INFO  com.normation.rudder.services.policies.TechniqueAcceptationUpdater - Automatically adding technique 'normation_com_wildcard_certificate' in category 'Root of active techniques's library (Active Techniques)' of active techniques library

This seems to be a consequence of #15575 (so from rudder 5.0.13).
The culprit looks like:

    def findCategory(sourcesCatNames: List[CategoryInfo], existings: FullActiveTechniqueCategory): (ActiveTechniqueCategoryId, String) = {
      if(sourcesCatNames.isEmpty ) (existings.id, existings.name)
      else {
        val catId = sourcesCatNames.head.id.trim
        existings.subCategories.find { cat => cat.id.value == catId} match {
          case None =>
            //create and go deeper
            createCategories(sourcesCatNames.map(x => CategoryInfo(x.id, x.name, x.description)), (existings.id, existings.name))
          case Some(cat) =>
            // continue !
            findCategory(sourcesCatNames.tail, cat)
        }
      }
    }

==> we don't check for name existance before attempting to create the new category.