I also looked at the source of the newer ypbind-mt package in the Testing branch and it appears to have the same issue.
- Bug#988178: nis: ypbind fails to start when already... Brian Morris
- Bug#988178: Newer ypbind-mt package also affec... Brian Morris
- Bug#988178: Newer ypbind-mt package also a... Francesco P. Lovergine
- Bug#988178: Newer ypbind-mt package al... Brian Morris