I can confirm this happens during a rebuild in my own sbuild chroots. The core issue appears to be that when the make rules call help2man, the version string provided is an empty string. Digging into d/rules, it looks like DEB_VERSION_UPSTREAM_REVISION is unset during the process, which is why it produces an empty string.
Replacing this with DEB_VERSION_UPSTREAM fixes this issue and properly only uses the upstream version part minus the Debian epochs. I'll get a fix pushed into Salsa and get it sponsored from there. Thomas
