It helps to look at release notes for clues. The very next checkin after release 2016.22 says:
"Paste modifications for how single effects paste in various situations. Fixes #549."
So I'm assuming you are copying a single effect because that's the behavior that changed. Now you have like 4 options on how a single cell is pasted.
1) You copy a single effect, select a single cell and hit Paste with Paste by Time mode. The result is the effect is pasted with the original duration.
2) You copy a single effect, select a single cell and hit Paste with Paste by Cell mode. The result is the effect is pasted to fit within the selected cell.
3) You copy a single effect, select multiple cells and hit Paste with Paste by Time mode. The result is the effect is pasted as one effect that spans the duration of the selected cells.
4) You copy a single effect, select multiple cells and hit Paste with Paste by Cell mode. The result is you get a copy of that effect pasted into every cell.