On Wed, 19 Feb 2020, Ludovic Courtès wrote:

> What does “cat /proc/sys/kernel/modprobe” return on the broken system?

/gnu/store/daq5zs7ni529zh3xxgyhidna52wa17js-modprobe

The contents of that file are:

"""
#!/gnu/store/1mkkv2caiqbdbbd256c4dirfi4kwsacv-guile-2.2.6/bin/guile --no-auto-compile
!#
(begin (setenv "LINUX_MODULE_DIRECTORY" "/run/booted-system/kernel/lib/modules")
        (apply execl "/run/current-system/profile/bin/modprobe"
                     (cons "/run/current-system/profile/bin/modprobe" (cdr (command-line)))))
"""

> I would expect 8b9cad01e9619f53dc5a65892ca6a09ca5de3447 to be suspect #1
> because it potentially leads to ‘LINUX_MODULE_DIRECTORY’ being unset in
> places where it used to be set before.

Based on the commit message, I would have expected that too, but 
205c1e04e04b9a9338c7219ff82bd13f000fb8c8 is the first bad commit for me as 
well. The above modprobe script is from a system at commit 
8b9cad01e9619f53dc5a65892ca6a09ca5de3447.

Best,
Jack