Expected behaviour
When markers are hidden because of small distances between points (large points, zoomed-out axis), markers still show on hover. Hover colors should match what they would be if those markers were not hidden.
Actual behaviour
Marker colors don't match the correct zone, though line colors do
Live demo with steps to reproduce
http://jsfiddle.net/ncchm8v1/
Affected browser(s)
Happens in both Firefox and Chrome in Linux, Chrome in Windows
Note, I mentioned this in issue a comment on #4670 but thought it might be better to open a new issue rather than reopen that one, as I'm not sure if they're related