Merge branch 'fix-dots-in-wiki-title' into 'master'

Fix dots in Wiki slug causing errors

### What does this MR do?

When a user enters in dots into the Wiki slug, an error occurs:

```
NoMethodError (undefined method `escaped_url_path' for nil:NilClass):
  app/models/wiki_page.rb:172:in `set_attributes'
  app/models/wiki_page.rb:191:in `save'
  app/models/wiki_page.rb:155:in `update'
  app/controllers/projects/wikis_controller.rb:49:in `update'
```

This MR fixes this problem.

### Are there points in the code the reviewer needs to double check?

See the problem below.

### Why was this MR needed?

The issue is that the `save` method gets called differently:

```ruby
def create(attr = {})
....
    save :create_page, title, content, format, message
```

or

```ruby
def update(new_content = "", format = :markdown, message = nil)
...
    save :update_page, @page, content, format, message
```

In the create case, title is the slug entered in by the user (e.g. `path/how-to-write-wiki-pages`).

In the update case, originally `@page.page` included the format extension (e.g.`path/how-to-write-wiki-pages.Markdown`). The method `page_title_and_dir` was trying to handle both cases and not doing the right thing. For example, calling `page_title_and_dir('test-1.2.3')` would result in:

```
path_title = test-1.2
path_dir = 3
```

### What are the relevant issue numbers / [Feature requests](http://feedback.gitlab.com/)?

Issues #1263, #431

This replaces !156

See merge request !419

1 files changed, 1 insertions, 0 deletions

diff --git a/CHANGELOG b/CHANGELOG
index 854f5c88bc3..08ba834b9c2 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,6 +2,7 @@ Please view this file on the master branch, on stable branches it's out of date.
 
 v 7.10.0 (unreleased)
   - Fix "Import projects from" button to show the correct instructions (Stan Hu)
+  - Fix dots in Wiki slugs causing errors (Stan Hu)
   - Update poltergeist to version 1.6.0 to support PhantomJS 2.0 (Zeger-Jan van de Weg)
   - Fix cross references when usernames, milestones, or project names contain underscores (Stan Hu)
   - enable line wrapping per default and remove the checkbox to toggle it (Hannes Rosenögger)