Archetypes unable to clear date field values

AT DatetimeWidget in Plone 5 (Products.Archetypes 1.10.x+) and in 1.x will not empty any existing set date/time value.

This is the culprit:

I'm fixing this on a fork or 1.x (PR soon), as such:

Fixing this for Plone 5 in Products.Archetypes master seems reasonable, but should I submit this as a pull request (with fix plus test) or just as an issue?


Pull requests are very welcome.