tests/test-journal-exists.t

packaging: add make target for linux wheels

Having linux wheels is going to helps system without compiler or python-dev
plus speed up the installation for everyone.

I followed the manylinux example repository
https://github.com/pypa/python-manylinux-demo
to add a make target (build-linux-wheels) using
official docker image to build python 2 linux wheels
for mercurial. It generates Python 2.6 and Python 2.7 for both
32 and 64 bits architectures.

I had to blacklist several test cases for various reasons:
* test-convert-git.t and test-subrepo-git.t because of the git version
* test-patchbomb-tls.t because of warning using tls 1.0
  It's likely because the docker image is based on centos 5.0 and
  openssl is outdated.

  $ 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
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  1 files, 1 changesets, 1 total revisions

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