This is a tad disconcerting.
I still have the USB installer configured as a repo. So when Yast asked for it, I plugged it in. But Yast still complained that it could not find that device.
Doing some checking, I noticed that the device name at the time that I installed this system (42.1) was
/dev/disk/by-id/scsi-1SanDisk.Cruzer..........20051233520F4F705D66-part2
That’s a copy/paste from part of the output of “zypper lr -d”.
The device name is normally “/dev/sdd2” on this machine. So to find the permanent ID, I used the command
- ls -l /dev/disk/by-id | grep sdd2
which told me that the device IDs available are:
/dev/disk/by-id/scsi-1SanDiskCruzer-part2
/dev/disk/by-id/scsi-SSanDisk_Cruzer_20051233520F4F705D66-part2
So something has changed.
Another check. I booted that USB. I booted it to the rescue system.
Using the same method (that “ls” command), I found that the rescue system saw the device IDs available as:
/dev/disk/by-id/scsi-1SanDisk.Cruzer..........20051233520F4F705D66-part2
/dev/disk/by-id/scsi-SSanDisk_Cruzer_20051233520F4F705D66-part2
So the software on that installer USB still recognizes the name used in the repo list. The currently installed software doesn’t. Some update must have changed the algorithm used to generate those names.
I’m now wondering if this change is a bug or a feature 
In the meantime, I’ll edit the file in “/etc/zypp/repos.d” and change to using the device-id that was valid both during install and now.