* build-aux/hydra/evaluate.scm <top level>: Add call to 'add-to-store'.
Use that as the 'file-name' attribute. Call 'primitive-load' in a
directory excursion to SOURCE.
* build-aux/hydra/guix-modular.scm: Remove 'eval-when' form that fiddled
with '%load-path'.
(build-job): Load 'build-aux/build-self.scm' and call the procedure it
returns.
* build-aux/hydra/evaluate.scm: The 'build-things' replacement no longer
calls 'exit'.
Ludovic Courtès