tests/test-journal-exists.t

rewriteutil: handle dropped commits when updating description hashes

In looking to leverage this with the absorb extension, the old -> new mapping
there allows the new value to be None.  We could filter that out and not pass it
to this method, but it seems worth a message to the user.  (I wonder if these
should be an info or warning, because it's unlikely people are using `-v`
regularly.)

Differential Revision: https://phab.mercurial-scm.org/D9181

  $ hg init
  $ echo a > a
  $ hg ci -Am0
  adding a

  $ hg -q clone . foo

  $ touch .hg/store/journal

  $ echo foo > a
  $ hg ci -Am0
  abort: abandoned transaction found!
  (run 'hg recover' to clean up transaction)
  [255]

  $ hg recover
  rolling back interrupted transaction
  (verify step skipped, run `hg verify` to check your repository content)

recover, explicit verify

  $ touch .hg/store/journal
  $ hg ci -Am0
  abort: abandoned transaction found!
  (run 'hg recover' to clean up transaction)
  [255]
  $ hg recover --verify
  rolling back interrupted transaction
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files

recover, no verify

  $ touch .hg/store/journal
  $ hg ci -Am0
  abort: abandoned transaction found!
  (run 'hg recover' to clean up transaction)
  [255]
  $ hg recover --no-verify
  rolling back interrupted transaction
  (verify step skipped, run `hg verify` to check your repository content)


Check that zero-size journals are correctly aborted:

#if unix-permissions no-root
  $ hg bundle -qa repo.hg
  $ chmod -w foo/.hg/store/00changelog.i

  $ hg -R foo unbundle repo.hg
  adding changesets
  abort: Permission denied: '$TESTTMP/foo/.hg/store/.00changelog.i-*' (glob)
  [255]

  $ if test -f foo/.hg/store/journal; then echo 'journal exists :-('; fi
#endif