If a user has an error in their terminal that looks something like the following:

error: Unable to rename file from '/filespace/b/bucky/.config/fish/fishd.tmp.RDqhYw' to '/filespace/b/bucky/.config/fish/fish_variables': Device or resource busy

Then they are likely using `fish` as their login shell for the Linux lab machines and are having errors with their NFS-mounted home directories. A fix for this issue is as follows (run the following commands, one by one, from a terminal that is NOT currently running the `fish` shell):

$ tmphome=$(mktemp -d)
$ export REAL_HOME=$HOME
$ HOME=$tmphome fish
> $ cp $HOME/.config/fish/fish_variables $REAL_HOME/.config/fish/fish_variables
> $ exit
$ rm -rf $tmphome
$ fish

Then everything should work without any errors.