Inconsistent rounded corners in stacked bar chart when a segment has zero value

[techjoyment]

When using rounded corners in a stacked bar chart, the rounding is applied inconsistently if one of the stack segments has a zero or missing value.

[lee00678]

@techjoyment we will look into this. Thanks for bringing it up.

[rokotyan]

Will be fixed in 1.6.5 #743