run-tests: exit cleanly if parallel run is interrupted If interrupted while running with "--jobs N", run-tests asynchronously spewed a bunch of output and backtraces from both the master and slave processes, leaving the terminal full of goop. This patch makes it behave more sensibly.

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  $ hg init

  $ echo '[Section]' >> $HGRCPATH
  $ echo 'KeY = Case Sensitive' >> $HGRCPATH
  $ echo 'key = lower case' >> $HGRCPATH

  $ hg showconfig Section
  Section.KeY=Case Sensitive
  Section.key=lower case