* Removed some dead code (successor stuff) from nix-push.
* Updated terminology in the tests (store expr -> drv path).
* Check that the deriver is set properly in the tests.
being created after the garbage collector has read the temproots
directory. This blocks the creation of new processes, but the
garbage collector could periodically release the GC lock to allow
them to run.
roots to a per-process temporary file in /nix/var/nix/temproots
while holding a write lock on that file. The garbage collector
acquires read locks on all those files, thus blocking further
progress in other Nix processes, and reads the sets of temporary
roots.
