darcs2git: handle the case when there is a convert error but tailor exists with status code 0
darcs2git: handle the case when there is a convert error but tailor exists with status code 0

vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam,vmiklos/vmexam