fixes issues for mr acceptance

app/models/repository.rb

@@ -759,8 +759,8 @@ class Repository
         update: options[:update]
       }
 
-      if commit_options[:previous_path]
-        commit_options[:file].merge!(previous_path: commit_options[:previous_path])
+      if options[:previous_path]
+        commit_options[:file][:previous_path] = options[:previous_path]
 
         Gitlab::Git::Blob.rename(raw_repository, commit_options)
       else

app/views/projects/blob/_editor.html.haml

@@ -4,11 +4,9 @@
       = icon('code-fork')
       = ref
     %span.editor-file-name
-      - if current_action?(:edit) && can?(current_user, :push_code, @project)
-        = text_field_tag 'file_name', params[:file_name], placeholder: @path,
+      -if current_action?(:edit) || current_action?(:update)
+        = text_field_tag 'file_name', (params[:file_name] or @path),
                                       class: 'form-control new-file-name'
-      - else
-        = @path
 
     - if current_action?(:new) || current_action?(:create)
       %span.editor-file-name