CPDF rounded clipping path adds a diagonal across the shape #3785

Cpdf::clippingRectangleRounded() builds the path around all four rounded corners, then after the top-left arc ends at the starting point (the left edge at y1 + h - rTL) it emits one more line to ($x1 + $rBL, $y1) before applying W n:

// after the top-left arc
$this->addContent(sprintf("\n%.3F %.3F l ", $x1 + $rBL, $y1));
$this->addContent(" W n");

That line crosses the clipped area diagonally from the top-left side to the bottom-left corner. With unequal corner radii it is especially clear, but it is present for all radii. The path should close along the rectangle's intended boundary without this extra diagonal.

Static source finding; no render test was run.