Define and use nullrev (revision of nullid) instead of -1.
abort: impossible time zone offset: 4444444
transaction abort!
rollback completed
abort: invalid date: '1\t15.1' see hg(1) manual page for details
transaction abort!
rollback completed
abort: invalid date: 'foo bar' see hg(1) manual page for details
transaction abort!
rollback completed
abort: invalid date: ' 1 4444' see hg(1) manual page for details
transaction abort!
rollback completed
abort: date exceeds 32 bits: 111111111111
transaction abort!
rollback completed
trouble committing bar!
abort: No such file or directory: .../test/bar