I think I've exhaustively searched for this, but maybe the issue is that most people don't need this function. In "editOnePic.php", the checkbox for "Read EXIF info again" is not implemented. I've checked the latest CVS versions of both 1.3 and 1.4 and in both, the variable $read_exif is assigned to the checkbox value but then nothing is done with it. Since the traditional EXIF operation is to grab the data only when viewing the normal image for the first time (and not on upload unless you are using the "sort by EXIF date" mod), I assume the implementation would be to remove the relevant record from the cpg_exif table and then let the data be grabbed again next time the image is viewed. But maybe since the checkbox is "Read EXIF info again", the EXIF info should be read immediately in the editOnePic.php script. I can write up the fix if necessary but I figured the developers should decide first how a feature not implemented but clearly intended to be implemented should be implemented ... if that makes any sense.
for the stable branch I suggest commenting the box out, a possible "real" fix should go into the devel banch imo, as any implementation would be a new feature that needs testing.
Commit it in the devel
As GauGau suggested, I commented out the checkbox and variable in stable. I haven't touched devel yet.
edit: Marking 'fixed' here, will add to to-do list for 1.5.