Huuuge speedup in the Hydra evaluator

Dependencies

• [2] RXVJFQ5A Evaluator cleanups
• [3] 3XTHEUMP * Implemented the clone feature.
• [*] OOQ2D3KC * Refactoring: move fetchInput out of hydra_scheduler into a separate

Change contents

• replacement in src/lib/Hydra/Helper/AddBuilds.pm at line 840
  [2.528]→[2.528:663](∅→∅)
  − my ($prevBuild) = $prevEval->builds->search({ job => $job->name, outPath => $outPath }, { rows => 1, columns => ['id'] });
  [2.528]

  [2.663]
  + my ($prevBuild) = $prevEval->builds->search(

  + # The "project" and "jobset" constraints are

  + # semantically unnecessary (because they're implied by

  + # the eval), but they give a factor 1000 speedup on

  + # the Nixpkgs jobset with PostgreSQL.

  + { project => $project->name, jobset => $jobset->name, job => $job->name, outPath => $outPath },

  + { rows => 1, columns => ['id'] });