Permission Denied on first installation step

My problem appears identical to the one discussed here:

Problem in installing olympe

But the solution was not applicable to me. The permissions on /dev/shm are set appropriately, and the change to /etc/fstab didn’t help.

I have a fresh Ubuntu installation (running in a VM) created for purposes of developing with Olympe. I try to execute the first (significant, after mkdir and cd) step of the instructions:

repo init -u

After a couple of warnings about missing gpg and git-related templates, I get a python stack trace that culminates in this line:

File “/snap/git-repo/18/usr/lib/python2.7/multiprocessing/”, line 75, in init
sl = self._semlock = _multiprocessing.SemLock(kind, value, maxvalue)
OSError: [Errno 13] Permission denied

I found a seemingly related issue on StackOverflow:

But the cause is inapplicable to my setup, i.e. the permissions on /dev/shm are already what the accepted answer says to change them to. And I made the suggested change to /etc/fstab anyway and rebooted, and it didn’t help

Any thoughts?