Script works in bash terminal but not in Shell build step in a Jenkins job

[morty]

I am running Jenkins on Ubuntu 15.10. I have the following bash script:

#!/bin/bash
STAGING_DIR="staging"

rm -Rf $STAGING_DIR
mkdir $STAGING_DIR
cd $STAGING_DIR

git clone [path-to-my-git-repo] .

virtualenv --no-site-packages virtual_django
source virtual_django/bin/activate
pip install django

python manage.py runserver 0.0.0.0:8000

When I run the above script in a shell build step the build just hangs with this in the build log:

Cloning into '.'...

New python executable in virtual_django/bin/python2

Also creating executable in virtual_django/bin/python

Installing setuptools, pip...done.

Running virtualenv with interpreter /usr/bin/python2

Downloading/unpacking django

Installing collected packages: django

Successfully installed django

Cleaning up...

When I run the same script from a terminal on the Ubuntu machine (under the jenkins user) it works fine and outputs:

Installing setuptools, pip...done.

Downloading/unpacking django

  Downloading Django-1.9.5-py2.py3-none-any.whl (6.6MB): 6.6MB downloaded

Installing collected packages: django

Successfully installed django

Cleaning up...

Performing system checks...

System check identified no issues (0 silenced).

You have unapplied migrations; your app may not work properly until they are applied.

Run 'python manage.py migrate' to apply them.

April 13, 2016 - 19:55:17

Django version 1.9.5, using settings 'mysite.settings'

Starting development server at http://0.0.0.0:8000/

Quit the server with CONTROL-C.

Any ideas why the above script hangs in the Jenkins job but works fine from the terminal?