usb-creator-gtk does not recognize Ubuntu PPC ISO images

Binary package hint: genisoimage

How to reproduce the bug:

1) install Ubuntu 11.04 on an intel-compatible PC
2) start system/administration/startup disk creator (usb-creator-gtk)
3) select an Ubuntu/PPC 11.04 ISO image...
4) ...but the ISO file does not appear "selected" as expected (selected dialog remains empty).

This is a long-term bug (I already experienced it in Ubuntu 9.04 and 9.10), due to limits of "isoinfo" utility contained in the "genisoimage" package.

Apparently, usb-creator-gtk verifies the correctness of the ISO image calling:
/usr/bin/isoinfo -J -i /tmp/natty-desktop-powerpc.iso -x /.disk/info

but isoinfo 1.1.11 complains "Unable to find Joliet SVD".

Mounting the same PPC ISO image as looped filesystem works OK (the ISO image mounts OK and its .disk/info file contains "Ubuntu 11.04 "Natty Narwhal" - Release powerpc (20110427.1)").

Funny, if I change /usr/bin/isoinfo with a shell script printing the "Ubuntu...powerpc..." string, the usb-creator-gtk works OK and correctly creates the USB startup disk.

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: usb-creator-gtk 0.2.28.3
ProcVersionSignature: Ubuntu 2.6.38-8.42-generic 2.6.38.2
Uname: Linux 2.6.38-8-generic i686
Architecture: i386
Date: Mon May 9 14:21:05 2011
InstallationMedia: Ubuntu 11.04 "Natty Narwhal" - Alpha i386 (20110202)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en
 PATH=(custom, user)
 LANG=it_IT.UTF-8
 LC_MESSAGES=en_GB.UTF-8
 SHELL=/bin/bash
SourcePackage: usb-creator
UpgradeStatus: No upgrade log present (probably fresh install)