Out of curiosity I did the same thing in script-fu:
(set! image (car (gimp-file-load RUN-NONINTERACTIVE filename filename)))
And it does the same thing - it sets the dirty flag.
Reading the Additional information in the procedure browser for gimp-image-clean-all
gives a clue:
This procedure sets the specified image's dirty count to
0, allowing operations to occur without having a 'dirtied'
image. This is especially useful for creating and loading
images which should not initially be considered dirty,
even though layers must be created, filled, and installed
in the image. Note that save plug-ins must NOT call this
function themselves after saving the image.
So, although you are only loading an image, GIMP is having to create layer(s) and fill them with the image - which it obviously counts as having modified the image.
This post has been edited by paynekj: 22 November 2011 - 09:00 AM