Comment 0 for bug 1000527

After fixing usb-creator so it builds, I tried it on a debian box and found a problem:
in install.py is a load of code to use syslinx-legacy and apropriate options either side of the 10.04 and 10.10 Ubuntu releases.

That fails if a debian iso has been burned onto the USB stick.

    target_os_ver, our_os_ver = self.os_vers()
      File "/usr/lib/python2.7/dist-packages/usbcreator/install.py",line 206, in os_vers
    target_os_ver = debian_support.Version(contents[1])
      File "/usr/lib/python2.7/dist-packages/debian/debian_support.py", line 172,
in __init__
    super(AptPkgVersion, self).__init__(version)
      File "/usr/lib/python2.7/dist-packages/debian/debian_support.py", line 91,
in __init__
    self.full_version = version
      File "/usr/lib/python2.7/dist-packages/debian/debian_support.py", line 117,
in __setattr__
    self._set_full_version(str(value))
      File "/usr/lib/python2.7/dist-packages/debian/debian_support.py", line 96,
in _set_full_version
    raise ValueError("Invalid version string %r" % version)
    ValueError: Invalid version string 'GNU/Linux'

This is because of this code:
if os.path.exists(os.path.join(self.target, '.disk', 'info')):
    with open(os.path.join(self.target, '.disk', 'info'),'r') as f:
        contents = f.readline().split()
    if len(contents) > 2:
        # Consider point releases the same as the initial release
        # (10.04.4 -> 10.04)
        target_os_ver = debian_support.Version(contents[1])

becuause .disk/info is:
Debian GNU/Linux wheezy-DI-a1 "Wheezy" - Official Snapshot amd64 NETINST Binary-1 20120512-00:39

so the code tries to parse "GNU/Linux" as debian version number and rightly fails.

BTW I'm not sure that the 'debian_support.Version' fn is really apropriate here as it seems to be designed for package version numbers not release numbers - mind you this works OK:
our_os_ver = debian_support.Version(
      lsb_release.get_distro_information()['RELEASE'])

My python is not good enough to work out what to do about this. You could just look for contents[3] and not use the 'Version' function. (There is a 'Release' fn which might be helpful here?)

Or perhaps better is to simply not do any of this checking on Debian as we've been on syslinux 2.4 since squeeze, and there isn't a syslinux-legacy package to use anyway. I'm not sure of the full implications here.

In fact how much do we care about people writing images older then 10.10 any more. Could it all just be simplified for Ubuntu too?

There is a lot of simplification possible in install_bootloader, mangle_syslinux, need_syslinux_legacy etc.

Someone who actually speaks python and is vaguely famliar with the code could presumably fix this without too much trouble.

Hope this is helpful to someone.