A job with some standard steps in it like:

• VirtualEnv Builder clean=True
  $ pip install -r requirements.txt

• VirtualEnv Builder clean=False
  $ python manage.py syncdb --noinput

• VirtualEnv Builder clean=False
  $ python manage.py migrate

• VirtualEnv Builder clean=False
  $ python manage.py tests

Will decide to create an entirely new virtualenv at one of the steps that have clean not set.

This of course breaks the build and makes the job useless

I had this multiple times before in other jobs and the only solution seems to be to clear out all the steps and recreate them and then hope that it will work as expected.