Pcbnew Gerber Export generates extra points in polygons

[St. Schulte]

Some CAM-processors stops plotting because at the end of some tracks there is an additional point (duplicated). Example:

G36*
X133318815Y-95218815D02*
G01*
X133239463Y-95315506D01*
…
X132685000Y-95185000D01*
X133360019Y-95185000D01*
X133318815Y-95218815D01* <=
X133318815Y-95218815D01* <=
G37*
X133318815Y-95218815D02*

here is X133318815Y-95218815D01* doubled.

In the specs the generation is declared as:
Syntax | Comments
G36* | Start a region
X200Y300000D02* | Move the current point to (2, 3)
G01* | Set linear interpolation
X700000D01* | Line segment to (7, 3)
Y100000D01* | Line segment to (7, 1)
X1100000Y500000D01* | Line segment to (11, 5)
X700000Y900000D01* | Line segment to (7, 9)
Y700000D01* | Line segment to (7, 7)
X200000D01* | Line segment to (2, 7)
Y300000D01* | Line segment to (2, 3)
G37* | Create the region by filling the contour

There is also a German thread about his (same data as above):
https://www.mikrocontroller.net/topic/482457

The data was created with KiCAD 5.1.4 (Windows and Linux), the errors were visualized by GC-Prevue (white X in the CAM-Scfreenshot).

[St. Schulte (steven0815)]

Only an idea:
In common/plotters/GERBER_plotter.cpp
Line 517+
    if( aFill )
    {
        fputs( "G36*\n", outputFile );

        MoveTo( aCornerList[0] );
        fputs( "G01*\n", outputFile ); // Set linear interpolation.

        for( unsigned ii = 1; ii < aCornerList.size(); ii++ )
            LineTo( aCornerList[ii] ); <== could here the last point also been included and then

        FinishTo( aCornerList[0] ); <== here repeated?
        fputs( "G37*\n", outputFile );
    }

[KiCad Janitor (kicad-janitor)]

Fixed in revision 4b2d801fec4b3f503e98723cab5395bcaa1c654b
https://git.launchpad.net/kicad/patch/?id=4b2d801fec4b3f503e98723cab5395bcaa1c654b