A change in recent systemd versions causes mount units to fail if the
mount point's path contains symlinks. OS versions since 1688.0.0 are
affected. The documentation on building custom kernel modules
included such a unit, lib-modules.mount, which has been updated to use
/etc/fstab instead.
https://coreos.com/os/docs/latest/kernel-modules.html
If you have configured systems by following the previous version of
this documentation, or otherwise provisioned systems using mount units
with a symlinked mount point path, please switch to /etc/fstab
(systemd's preferred option) or update the mount units to use the real
paths.