Add a dependency_lookup configuration option to enable (slow) dependency lookup in queue. This behaviour was disabled temporarily in accefbb79 due to slowness in very large queues, but some people might be dependent on it, so it is configurable until the previous behaviour is implemented more efficiently.

Dependencies

• [2] LSPRR4TK hydra-queue-runner: Disable findBuildDependencyInQueue for now
• [3] WTUBAA5Q hydra-queue-runner: Handle restarted builds whose derivation is gone
• [4] OV7F5M3E Merge branch 'queue-17'
• [5] YEXD7CBK Fix findBuildDependencyInQueue
• [6] TPSCSZKX Speed up findBuildDependencyInQueue
• [*] 7YBYT2LQ

Change contents

• edit in src/script/hydra-queue-runner at line 22
  [8.7967]

  [8.7967]
  + my $config = getHydraConfig();
• replacement in src/script/hydra-queue-runner at line 52
  [3.36]→[2.0:26](∅→∅)
  − return undef; # FIXME
  [3.36]

  [3.0]
  + return undef if !($config->{dependency_lookup} // 0); # FIXME