Table cell padding offsets the entire cell border in RTL

My FO document in LR writing mode lays out fine, with three row headers left aligned with some left padding.  Roughly the same document except with the writing mode / alignment / padding flipped doesn't render correctly.  The cell border is shifted, almost acting like a margin, but spills over into other cells.  I also tried flipping the left/right padding in RTL, just to see what would happen, and the border was pushed the other way.  I didn't upload examples for padding-start/end, but they were the same.