Unexpected error on automated build

I’m trying to let my Image build on Docker Hub and getting a failed build with the message Build failed: Unexpected error.

The complete output is:

Starting to clone
Cloning into '.'...
Note: checking out '2def0101328c9ac33ef7cf405ca04b2c5f60778a'.

u are in 'detached HEAD' state. You can look around, make experimental
  changes and commit them, and you can discard any commits you make in this
state without impacting any branches by performing another checkout.

If you want to create a new branch to retain commits you create, you may
do so (now or later) by using -b with the checkout command again. Example:

  git checkout -b new_branch_name

Cloning done
Starting Build
KernelVersion: 3.13.0-40-generic
Os: linux
BuildTime: 2016-02-22T21:37:01.910365059+00:00
ApiVersion: 1.22
Version: 1.10.2
GitCommit: c3959b1
Arch: amd64
GoVersion: go1.5.3
Starting build of index.docker.io/itsecur/seafile:5.1.0...
Unexpected error

It seems not to be an issue with the Dockerfile/Scripts itself, since the build seems to fail before even looking at any of those.

Nevermind, it has been solved, it was indeed an error in the Dockerfile, not a very helpful error though (building it locally showed the error though).