Improve logging for aborts

Dependencies

• [2] QJRDO2B4 Simplify retry handling
• [3] RYTQLATY Keep track of failed paths in the Hydra database
• [4] OCZ4LSGG Automatically retry aborted builds
• [5] HHOMBU7G hydra-queue-runner: Implement timeouts
• [*] 24BMQDZA Start of single-process hydra-queue-runner

Change contents

• edit in src/hydra-queue-runner/hydra-queue-runner.cc at line 1073
  [3.1234]→[3.4223:4382](∅→∅)
  − printMsg(lvlError, format("irregular failure building ‘%1%’ on ‘%2%’: %3%")

  − % step->drvPath % machine->sshName % e.msg());
• edit in src/hydra-queue-runner/hydra-queue-runner.cc at line 1083
  [3.4463]

  [2.108]
  + printMsg(lvlError, format("irregular failure building ‘%1%’ on ‘%2%’: %3%")

  + % step->drvPath % machine->sshName % result.errorMsg);