Activity which under 0.6.2 displayed as "yesterday" / "2 
days ago" under 0.6.3 displays as "tomorrow" / "in 2 
days".

Sorting by activity has the same ordering as before -- 
only the display seems affected.

I suspect Date.__sub__: the sign applied to the resulting 
Interval when two dates are subtracted appears to have 
changed between the releases.

But date.py feels like deep magic to me -- as a 
temporary workaround I inverted the subtraction in 
templating.DateHTMLProperty.reldate, which gets my 
tracker displaying correctly again.