Fix Mercurial input fetching if a cached input has been GC'ed

Dependencies

• [2] O25D52TA initial support for mercurial
• [3] OOQ2D3KC * Refactoring: move fetchInput out of hydra_scheduler into a separate
• [4] 2WRTOU2Z Cleanup
• [5] KQS7DSKJ * Clean up indentation.
• [6] G7XYM6MU use local clone to limit bandwidth usage

Change contents

• replacement in src/lib/Hydra/Helper/AddBuilds.pm at line 141
  [3.1350]→[3.1350:1410](∅→∅)
  − $db->resultset('CachedPathInputs')->create(
  [3.1350]

  [3.1410]
  + $db->resultset('CachedPathInputs')->update_or_create(
• replacement in src/lib/Hydra/Helper/AddBuilds.pm at line 570
  [2.2091]→[2.2091:2145](∅→∅)
  − $db->resultset('CachedHgInputs')->create(
  [2.2091]

  [2.2145]
  + $db->resultset('CachedHgInputs')->update_or_create(