TypeError /usr/bin/testdrive when downloading using HTTP

Binary package hint: testdrive

When testdrives downloads an ISO using HTTP (like http://releases.ubuntu.com/9.10/ubuntu-9.10-desktop-amd64.iso), it will crash after the successful download with the following traceback:

Traceback (most recent call last):
  File "/usr/bin/testdrive", line 366, in <module>
    main()
  File "/usr/bin/testdrive", line 314, in main
    run_or_die(cmd)
  File "/usr/bin/testdrive", line 103, in run_or_die
    if run(cmd) != 0:
  File "/usr/bin/testdrive", line 100, in run
    return(os.system(cmd))
TypeError: system() argument 1 must be string, not None

The reason is that TestDrive.get_proto returns None when the download using zsync succeeded, rather than 0 (which indicates success). It looks to me as if a 'return 0' statement is missing on line 224 of testdrive.py.

After some investigation, I noticed that there might be another underlying problem. When adding 'return 0', testdrive continues with the following output:

Creating disk image [/home/lantash/.cache/testdrive/img/testdrive-disk-1py09v.img]...
Formatting '/home/lantash/.cache/testdrive/img/testdrive-disk-1py09v.img', fmt=qcow2 size=6442450944 encryption=off cluster_size=0
INFO: Launching Virtual Machine...
Running the Virtual Machine...
qemu: could not open disk image /home/lantash/.cache/testdrive/iso/other_ubuntu-9.10-desktop-amd64.iso: No such file or directory

The prefix other_ should not have been added.

ProblemType: Bug
DistroRelease: Ubuntu 10.10
Package: testdrive 2.4-0ubuntu1
ProcVersionSignature: Ubuntu 2.6.35-6.9-generic 2.6.35-rc3
Uname: Linux 2.6.35-6-generic x86_64
Architecture: amd64
Date: Wed Jul 7 10:03:53 2010
InstallationMedia: Ubuntu 10.10 "Maverick Meerkat" - Alpha amd64 (20100624)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en
 LANG=de_CH.utf8
 SHELL=/bin/bash
SourcePackage: testdrive