For TIFF-like images, non-intrusive writing is not used when it should
Simple changes to TIFF-like images are written using the intrusive write-algorithm. The following command demonstrates the problem:
exiv2 -Qd -a1 image.tiff
Some of the logic related to the image tags introduced with #668 seems to essentially disable the use of non-intrusive writing for TIFF-like images.
(Reported by Thomas Lotze in a forum post)