Don't pass an undefined input

Dependencies

• [2] KQS7DSKJ * Clean up indentation.
• [3] OOQ2D3KC * Refactoring: move fetchInput out of hydra_scheduler into a separate
• [4] PMNWRTGJ Add multiple output support

Change contents

• replacement in src/lib/Hydra/Helper/AddBuilds.pm at line 92
  [2.4386]→[2.4386:4408](∅→∅)
  − return undef;
  [2.4386]

  [2.4408]
  + return ();