cmdutil: replace unix pipe handshake with file lock
The pipe handshake cannot be implemented with Windows detached process, which
disables handle inheritance.
Fix 2/3 for issue421
adding a
abort: abandoned transaction found - run 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
adding changesets
abort: Permission denied