The string you give IS an invalid date. There is no valid time: "00:20:58 AM". AM/PM times have hours in the 1-12 range (not 0).
The "problem" you're encountering is that Date::Manip 5.xx was far too flexible and would generally find a date, even if it wasn't completely correct, so 5.xx did parse this.
Date::Manip 6.xx actually is much more rigid about only accepting valid dates, so it reports this as invalid (which is correct).
Of course, if you remove the "AM" and just parse the time as "00:20:58", it'll find a valid time there.
Tue Jul 16 08:00:28 2013The RT System itself - Status changed from 'new' to 'open'
Tue Jul 16 08:00:29 2013sbeck [...] cpan.org - Status changed from 'open' to 'resolved'
Ah, my bad. Of course, it should be 12 AM and not 0 AM!
Sorry to have troubled you. I was in the throes of a lot of data
correction and couldn't believe it when data that had earlier been
parsed successfully (or so I thought) threw up an error.
Regards,
Sameer