Bug#590805: python-debian: Older versions of apt_pkg don't have TagFile

[Jelmer Vernooij]

Package: python-debian
Version: 0.1.16ubuntu1
Severity: normal

Older versions of apt_pkg don't have a TagFile class, making the
python-debian testsuite fail with these versions of apt_pkg. 

Attached patch makes python-debian only use apt_pkg for iterating over 
deb822 style paragraphs using apt_pkg if TagFile is present.

-- System Information:
Debian Release: squeeze/sid
  APT prefers maverick-updates
  APT policy: (500, 'maverick-updates'), (500, 'maverick-security'), (500, 'maverick-backports'), (500, 'maverick')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.35-11-generic (SMP w/4 CPU cores)
Locale: LANG=en_US.UTF-8, LC_CTYPE=en_US.UTF-8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages python-debian depends on:
ii  python                   2.6.5-10ubuntu1 interactive high-level object-orie
ii  python-apt               0.7.95ubuntu2   Python interface to libapt-pkg
ii  python-support           1.0.9ubuntu1    automated rebuilding support for P

python-debian recommends no packages.

Versions of packages python-debian suggests:
ii  gpgv                     1.4.10-2ubuntu2 GNU privacy guard - signature veri

-- no debconf information