dateutil: correct default for Ymd in parsedate The code uses `0` for the default value of Ymd (year, month, and day), which seems suboptimal. For example, these will fail to parse: dateutil.parsedate('2000', formats=dateutil.extendeddateformats) dateutil.parsedate('Jan 2000', formats=dateutil.extendeddateformats) Fix it by providing sane defaults (1 instead of 0) for year, month, and day. The suboptimal behavior was introduced by 91bc001a592 (2010-12-29, "date: fix matching of underspecified date ranges"), which does not seem to justify the current behavior. Note end-users should not notice the subtle issue, because there are no formats in `defaultdateformats` that allow an explicit year with omitted month, or an explicit month with omitted day. Differential Revision: https://phab.mercurial-scm.org/D7520