tests/test-config-case.t

phase: make if abort on nullid for the good reason

The good reason being you cannot call retractboundary() on nullid, not
revset.set() cannot resolve '-1'.

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

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