$ cat << EOF > buggylocking.py

  > """A small extension that acquire locks in the wrong order

  > """

  > 

  > from mercurial import cmdutil, repair, revset

  > 

  > cmdtable = {}

  > command = cmdutil.command(cmdtable)

  > 

  > @command('buggylocking', [], '')

  > def buggylocking(ui, repo):

  >     tr = repo.transaction('buggy')

  >     lo = repo.lock()

  >     wl = repo.wlock()

  >     wl.release()

  >     lo.release()

  > 

  > @command('properlocking', [], '')

  > def properlocking(ui, repo):

  >     """check that reentrance is fine"""

  >     wl = repo.wlock()

  >     lo = repo.lock()

  >     tr = repo.transaction('proper')

  >     tr2 = repo.transaction('proper')

  >     lo2 = repo.lock()

  >     wl2 = repo.wlock()

  >     wl2.release()

  >     lo2.release()

  >     tr2.close()

  >     tr.close()

  >     lo.release()

  >     wl.release()

  > 

  > @command('nowaitlocking', [], '')

  > def nowaitlocking(ui, repo):

  >     lo = repo.lock()

  >     wl = repo.wlock(wait=False)

  >     wl.release()

  >     lo.release()

  > 

  > @command('stripintr', [], '')

  > def stripintr(ui, repo):

  >     lo = repo.lock()

  >     tr = repo.transaction('foobar')

  >     try:

  >         repair.strip(repo.ui, repo, [repo['.'].node()])

  >     finally:

  >         lo.release()

  > 

  > def oldstylerevset(repo, subset, x):

  >     return list(subset)

  > 

  > revset.symbols['oldstyle'] = oldstylerevset

  > EOF

  $ cat << EOF >> $HGRCPATH

  > [extensions]

  > buggylocking=$TESTTMP/buggylocking.py

  > [devel]

  > all-warnings=1

  > EOF

  $ hg init lock-checker

  $ cd lock-checker

  $ hg buggylocking

  devel-warn: transaction with no lock at: $TESTTMP/buggylocking.py:11 (buggylocking)

  devel-warn: "wlock" acquired after "lock" at: $TESTTMP/buggylocking.py:13 (buggylocking)

  $ cat << EOF >> $HGRCPATH

  > [devel]

  > all=0

  > check-locks=1

  > EOF

  $ hg buggylocking

  devel-warn: transaction with no lock at: $TESTTMP/buggylocking.py:11 (buggylocking)

  devel-warn: "wlock" acquired after "lock" at: $TESTTMP/buggylocking.py:13 (buggylocking)

  $ hg buggylocking --traceback

  devel-warn: transaction with no lock at:

   */hg:* in * (glob)

   */mercurial/dispatch.py:* in run (glob)

   */mercurial/dispatch.py:* in dispatch (glob)

   */mercurial/dispatch.py:* in _runcatch (glob)

   */mercurial/dispatch.py:* in _dispatch (glob)

   */mercurial/dispatch.py:* in runcommand (glob)

   */mercurial/dispatch.py:* in _runcommand (glob)

   */mercurial/dispatch.py:* in checkargs (glob)

   */mercurial/dispatch.py:* in <lambda> (glob)

   */mercurial/util.py:* in check (glob)

   $TESTTMP/buggylocking.py:* in buggylocking (glob)

  devel-warn: "wlock" acquired after "lock" at:

   */hg:* in * (glob)

   */mercurial/dispatch.py:* in run (glob)

   */mercurial/dispatch.py:* in dispatch (glob)

   */mercurial/dispatch.py:* in _runcatch (glob)

   */mercurial/dispatch.py:* in _dispatch (glob)

   */mercurial/dispatch.py:* in runcommand (glob)

   */mercurial/dispatch.py:* in _runcommand (glob)

   */mercurial/dispatch.py:* in checkargs (glob)

   */mercurial/dispatch.py:* in <lambda> (glob)

   */mercurial/util.py:* in check (glob)

   $TESTTMP/buggylocking.py:* in buggylocking (glob)

  $ hg properlocking

  $ hg nowaitlocking

  $ echo a > a

  $ hg add a

  $ hg commit -m a

  $ hg stripintr

  saved backup bundle to $TESTTMP/lock-checker/.hg/strip-backup/cb9a9f314b8b-cc5ccb0b-backup.hg (glob)

  abort: programming error: cannot strip from inside a transaction

  (contact your extension maintainer)

  [255]

  $ hg log -r "oldstyle()" -T '{rev}\n'

  devel-warn: revset "oldstyle" use list instead of smartset, (upgrade your code) at: */mercurial/revset.py:* (mfunc) (glob)

  0

  $ cd ..