bug#58668: unable to mount second LUKS drive after reboot

[bdju]

I had 228 days of uptime and had changed out my second drive for a
bigger one and modified my config.scm accordingly. Upon reboot I was not
able to mount it or finish booting because of it, even though the
passphrase for my root drive was accepted fine.

I was able to boot this very same new drive after selecting a generation
from August 2nd. I thought at first that this generation was before I
had put the new drive configuration into place, but I noticed two
things:
1) the drive was mounted, I could see the files
2) upon looking over the version of my config.scm used in the booted
system, the new drive configuration was already in place after all

I also verified upon nckx's recommendation that the version of
cryptsetup used hasn't changed in this time. (2.7.3)

The working generation uses the following commit:
e6480571a094e27dc50db2b42334f17a6d1957d4

I realize this report is somewhat light on info, so let me know what
else I can try to provide.