tests/test-hup.t

rebase: mention --rev in the help

This changeset adds a small mention of it in the help to prevent
confusion. This small addition references online help that is easier to
update and improve at release time.

Following Wagner Bruna's advice, this is added in a plain new paragraph
to not invalidate current translation this close to the release.

Test hangup signal in the middle of transaction

  $ "$TESTDIR/hghave" serve fifo || exit 80
  $ hg init
  $ mkfifo p
  $ hg serve --stdio < p 1>out 2>&1 &
  $ P=$!

Do test while holding fifo open

  $ (
  > echo lock
  > echo addchangegroup
  > while [ ! -s .hg/store/journal ]; do sleep 0; done
  > kill -HUP $P
  > ) > p

  $ wait
  $ cat out
  0
  0
  adding changesets
  transaction abort!
  rollback completed
  killed!

  $ echo .hg/* .hg/store/*
  .hg/00changelog.i .hg/journal.bookmarks .hg/journal.branch .hg/journal.desc .hg/journal.dirstate .hg/requires .hg/store .hg/store/00changelog.i .hg/store/00changelog.i.a .hg/store/journal.phaseroots