None no longer matches zero-length string on CharField

[Simon Litchfield]

I've just updated from 1.5 stable to latest commit aaec4f2bd8a63b3dceebad7804c5897e7874833d.

Model.objects.filter(mycharfield=None) used to return instances where mycharfield is actually a zero-length string.

Now, it seems I need to explicitly specify Model.objects.filter(mycharfield='')

Minor change, but the implications could be pretty severe for some apps.

Suggest either reverting to previous behaviour or updating the "backwards incompatible changes" list.

[Simon Charette]

Dupe of #20102.