Post receive hooks fail if /home/git/repositories is a symlink

Created by: Razer6

If home/git/repositories is a symlink all post receive hooks fail with

gitlab:1276 on POST_RECEIVE at just now
Class
PostReceive
Arguments
"rpool/repositories/repositories/root/test13"
"0000000000000000000000000000000000000000"
"5ad1a2184774efe3e5a916e49f09540d88ebce90"
"refs/heads/master"
"admin_local_host_1356345379"
Exception
NoMethodError
Error
undefined method `id' for nil:NilClass

gitlab:check is green. I recognized this on my production server and could reproduce it on my development VM. Running on 4.1.0pre c8ba5c2d

Related to #2359 (closed)