Revert "🐛 Fixed importer duplicate detection for posts"

refs #8717

- we decided to not changing the current importer behaviour
- no slug duplication detection means, importing posts can result in duplicates

core/server/data/importer/importers/data/index.js

@@ -42,7 +42,6 @@ DataImporter = {
         if (importOptions && importOptions.importPersistUser) {
             modelOptions.importPersistUser = importOptions.importPersistUser;
         }
-
         this.init(importData);
 
         return models.Base.transaction(function (transacting) {

core/server/models/base/index.js

@@ -774,12 +774,6 @@ ghostBookshelf.Model = ghostBookshelf.Model.extend({
             if (!slug) {
                 slug = baseName;
             }
-
-            // CASE: no slug generation on import, see https://github.com/TryGhost/Ghost/issues/8717
-            if (options.importing) {
-                return slug;
-            }
-
             // Test for duplicate slugs.
             return checkIfSlugExists(slug);
         });

core/test/integration/data/importer/importers/data_spec.js

@@ -394,8 +394,6 @@ describe('Import', function () {
                 exportData = exported;
                 return dataImporter.doImport(exportData);
             }).then(function (importedData) {
-                importedData.data.posts.length.should.eql(1);
-
                 importedData.problems.length.should.eql(3);
                 importedData.problems[0].message.should.eql('Entry was not imported and ignored. Detected duplicated entry.');
                 importedData.problems[0].help.should.eql('Tag');