Merge branch 'patch-1' into 'master'

GitLab 8.4 uses gitlab-shell v2.6.10

While upgrading to GitLab 8.3 to 8.4 there was a warning massage for using GitLab 8.3 with gitlab-shell v2.6.9 so I changed gitlab-shell version to v2.6.10 and it worked.

See merge request !2555

doc/update/8.3-to-8.4.md

@@ -37,7 +37,7 @@ sudo -u git -H git checkout 8-4-stable-ee
 ```bash
 cd /home/git/gitlab-shell
 sudo -u git -H git fetch --all
-sudo -u git -H git checkout v2.6.9
+sudo -u git -H git checkout v2.6.10
 ```
 
 ### 5. Update gitlab-workhorse