Handle better broken disks
Handle better broken disks

While running burnin:
  File "/usr/lib/python2.4/site-packages/ganeti/objects.py", line 497, in __str__
    val += ", size=%dm)>" % self.size
TypeError: int argument required

This happened while handling another error, so we lose the original
error information.

So we should try to handle this better.

Reviewed-by: ultrotter

apyrgio/snf-ganeti,apyrgio/ganeti,leshchevds/ganeti,apyrgio/ganeti,ganeti/ganeti,ganeti/ganeti,dimara/ganeti,mbakke/ganeti,yiannist/ganeti,bitemyapp/ganeti,yiannist/ganeti,andir/ganeti,apyrgio/snf-ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,leshchevds/ganeti,andir/ganeti,leshchevds/ganeti,onponomarev/ganeti,ganeti/ganeti,yiannist/ganeti,andir/ganeti,dimara/ganeti,mbakke/ganeti,ganeti-github-testing/ganeti-test-1,onponomarev/ganeti,grnet/snf-ganeti,grnet/snf-ganeti,bitemyapp/ganeti