Remove unused assignment

Dependencies

• [2] NB2VOKIR Include names of committers in HipChat notifications
• [3] BEFHUCGN Factor a getResponsibleAuthors helper out of the HipChatNotification
• [4] ZDEHAFHV Add a plugin for HipChat notification

Change contents

• edit in src/lib/Hydra/Plugin/HipChatNotification.pm at line 40
  [2.1987]→[2.1987:2076](∅→∅),[2.2728]→[2.2728:2729](∅→∅)
  − # Determine who broke/fixed the build.

  − my $prevBuild = getPreviousBuild($build);

  −