I added a check for exif extension for Flyspray 1.0 RC1 .
The exif_imagetype() is currently only used one time in the whole Flyspray source for uploading the Flyspray logo and is not "superimportant" if you are the only admin.
So if your webhosting does not have the php exif extension enabled, you can remove that exif_imagetype() function call as a quickfix.
Around includes/modify.inc.php line 1163:
replace
if($_FILES["logo"]["error"] == 0 && exif_imagetype($_FILES["logo"]["tmp_name"]) ) {
with
if($_FILES["logo"]["error"] == 0) {
You can write also a bug report on
bugs.flyspray.org, so this issue can be addressed in the right manner in future releases and the section gets reviewed.