Please describe the problem:
Sometimes when I scale an image with the Image, Scale Image action the result turns up with one horizontal and two vertical bands with a width of one pixel each. If I save the image, the resulting file keeps the bands.

Steps to reproduce:
The source images I'm working with now are in TIFF format with dimensions 1407x2126 and 2900 DPI (that's what the photo lab's scanner gives me). I go to Image, Scale Image and pick the Lanczos3 method to scale that to 1200x794 at 72 DPI.

Actual results:
One black horizontal band appears at pixel offset 397 (output_height * .5) and two vertical ones appear at 300 and 900 (output_width * .25 and * .75, respectively).

Expected results:
No black bands would appear.

Does this happen every time?
No, only occasionally. As a matter of fact, the easiest workaround is to undo the operation and repeat it again with the steps detailed above. Simply going forward in the history after undo does not eliminate the bands.

Other information:
I have never seen this with the 2.2 version series. I think I might have seen this once with the 2.4.0 release candidates and today I saw it two or three times in 7-8 scale operations that I ran.