In the absence of expertise: layman's fix for the following error:

In the absence of expertise: layman's fix for the following error:

  File "pym/portage/dbapi/vartree.py", line 1189, in unmerge
    plib_registry.unregister(self.mycpv, self.settings["SLOT"], self.settings["COUNTER"])
  File "pym/portage/dbapi/vartree.py", line 100, in unregister
    self.register(cpv, slot, counter, [])
  File "pym/portage/dbapi/vartree.py", line 86, in register
    and self._data[cps][0] == cpv and int(self._data[cps][1]) == int(counter):
ValueError: invalid literal for int() with base 10: ''

COUNTER appears to be empty quite often, in this case it is often and
called by some preserved-libs stuff.  I just replace counter with an
explicit 0 in case counter == "".

svn path=/main/branches/prefix/; revision=9894