The official Debian kernel building tools are a thing of wonder. But, it didn’t do what I wanted, which was to build the exact version of the kernel that I’m running. I guess it is only ever used to build the latest version.
Also, reportbug failed (it was unable to get the list of open bugs for this package from the Bug Tracking System) — I used debian-bug in debian-el package (as noted at the bottom of this page). To actually send the mail, use ctrl-c ctrl-s in the mail buffer (or ctrl-c ctrl-c if you want to send the email and exit emacs).
Maybe I misunderstood … maybe the -5 is not the patch level I’m aiming for. We shall see.
No, the -5 is the “ABI” level, and has nothing to do with the Debian patch level. So there was no bug. I was supposed to build with all the patches. Live and learn …