Merge branch 'workhorse-0.6.4' into 'master'

Use gitlab-workhorse 0.6.4

This fixes a bug in 8.5.0.rc1 where downloading Git blobs through the API is broken.

See merge request !2794

GITLAB_WORKHORSE_VERSION

-0.6.3
+0.6.4

doc/install/installation.md

@@ -358,7 +358,7 @@ GitLab Shell is an SSH access and repository management software developed speci
     cd /home/git
     sudo -u git -H git clone https://gitlab.com/gitlab-org/gitlab-workhorse.git
     cd gitlab-workhorse
-    sudo -u git -H git checkout 0.6.3
+    sudo -u git -H git checkout 0.6.4
     sudo -u git -H make
 
 ### Initialize Database and Activate Advanced Features

doc/update/8.4-to-8.5.md

@@ -49,7 +49,7 @@ GitLab 8.1.
 ```bash
 cd /home/git/gitlab-workhorse
 sudo -u git -H git fetch --all
-sudo -u git -H git checkout 0.6.3
+sudo -u git -H git checkout 0.6.4
 sudo -u git -H make
 ```