[Piuparts-reports] problem with piuparts-slave detected

[piuparts slave]

Either a test is running for a very long time (more than 90 minutes),
or piuparts-slave hangs or is not running at all or wasn't started with
~piupartss/bin/slave_run - please investigate and take appropriate measures!

    return self._interpolate(section, option, value, d)
  File "/usr/lib/python2.7/ConfigParser.py", line 669, in _interpolate
    option, section, rawval, e.args[0])
ConfigParser.InterpolationMissingOptionError: Bad value substitution:
        section: [sid-merged-usr]
        option : chroot-tgz
        key    : arch
        rawval : %(distro)s-merged-usr_%(arch)s.tgz

piupartss at piu-slave-bm-a:/srv/piuparts.debian.org/slave/1$