Merge branch '23866-builds-dropdown' into 'master'

Increase z index on fixed mr tabs

Before:   
<img src="/uploads/e890a4f185af87b66251d744fbe840d5/Screen_Shot_2016-10-26_at_11.58.45_AM.png" width="400px">

After:   
<img src="/uploads/0bbf72888f6a47bd3027ee7dfff542da/Screen_Shot_2016-10-26_at_11.58.28_AM.png" width="400px">
Closes #23866

See merge request !7124

CHANGELOG.md

@@ -29,6 +29,9 @@ Please view this file on the master branch, on stable branches it's out of date.
   - Fix documents and comments on Build API `scope`
   - Refactor email, use setter method instead AR callbacks for email attribute (Semyon Pupkov)
 
+## 8.13.2
+  - Fix builds dropdown overlapping bug !7124
+
 ## 8.13.1 (2016-10-25)
   - Fix branch protection API. !6215
   - Fix hidden pipeline graph on commit and MR page. !6895

app/assets/stylesheets/pages/merge_requests.scss

@@ -439,12 +439,12 @@
 }
 
 .merge-request-tabs-holder {
-  background-color: #fff;
+  background-color: $white-light;
 
   &.affix {
     top: 100px;
     left: 0;
-    z-index: 9;
+    z-index: 10;
     transition: right .15s;
   }