Debsecan suddenly failing

["Aneurin Price" <aneurin.price@gmail.com>]

Hi,

I'm using Debsecan (acquired from
http://git.enyo.de/fw/debian/debsecan.git/debsecan.py about 6 weeks
ago) on a system running Sarge.

I have a cron job running "debsecan.py --suite sarge --format report"
as user "nobody" nightly which has been running fine for several
weeks, until last night. This morning's report is as follows:

Traceback (most recent call last):
  File "/usr/local/bin/debsecan.py", line 1356, in ?
    rate_system(target, options, fetch_data(options, config), history)
  File "/usr/local/bin/debsecan.py", line 1333, in rate_system
    if v.is_vulnerable (bp, sp):
  File "/usr/local/bin/debsecan.py", line 483, in is_vulnerable
    self._parse()
  File "/usr/local/bin/debsecan.py", line 515, in _parse
    self.unstable_version = Version(self.unstable_version)
  File "/usr/local/bin/debsecan.py", line 93, in __init__
    self.__parsed = self.__parse(version)
  File "/usr/local/bin/debsecan.py", line 112, in __parse
    raise ValueError, "invalid Debian version string"
ValueError: invalid Debian version string

Running debsecan.py with any other options (or none) also produced the
same error. Installing "python-apt" fixed the problem, but I'm still
rather concerned - Saturday night's job ran fine, so I can't see why a
problem would suddenly arise like this. The system hasn't been
modified in between to my knowledge - I'm the only person who ever
logs into it and I haven't touched it over the weekend. Only port 25
is open to the internet so I find it very unlikely that it's been
broken into, and there aren't any automated "apt-get upgrade"s or
anything like that, so I'm at a loss to explain this.

Does anybody have any ideas as to why this error might have appeared
so unexpectedly?

Thanks for your time,
Aneurin Price