Off-by-one error in contribution graph data

Click around in the contribution graph, and you'll see that the activities list shows the contributions from the previous day.

STR:

1. Visit https://gitlab.com/u/sytses
2. Click the square for Wednesday April 29, 2015 describing 0 contributions.
3. Note that 1 item appears in the contributions list.
4. Click the square for April 30 describing 9 contributions.
5. Note that 0 items are shown in the contributions list.
6. Click the square for May 1 showing 3 contributions.
7. Note that 9 items appear in the contributions list.

Clicking around some more shows that the data populating the contributions list is consistently off by one wrt the elements in the calendar heatmap.