[Nix-dev] Troubles with Hydra's failure cache

[Ludovic Courtès]

Hello,

Hydra maintains a cache of build failures, IIRC.  It's a problem when a
build fails due to some external interference, such as a network issue
among machines of the build farm or the infamous GC bug.

For example, Ant has been broken for several days because of the
latter.  However, its Nix expression didn't change since it failed, so
it's not being rebuilt.  See, e.g., http://hydra.nixos.org/build/54803 .

How can it be handled?  Could Hydra be extended (fixed?) to distinguish
between build failures and transient failures like this?

Thanks,
Ludo'.