Merge branch 'repo-list-root-caching' into 'master'

Fixed apollo caching of the root repository file listing

See merge request gitlab-org/gitlab-ce!30409

app/assets/javascripts/repository/components/table/index.vue

@@ -76,7 +76,7 @@ export default {
           variables: {
             projectPath: this.projectPath,
             ref: this.ref,
-            path: this.path,
+            path: this.path || '/',
             nextPageCursor: this.nextPageCursor,
             pageSize: PAGE_SIZE,
           },