sucommand that's now being packaged with Debian sid has significant change in behavior. In the past, when you did an:
the PATH would get set to root's PATH. Now, it remains the user's path:
This means you won't pick up
$ su Password: # echo $PATH /home/mithat/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games:/snap/bin
/usr/sbinwhere a lot of commands you'd typically use with root privileges live.
The fix to this is that you now have to append a dash to the command:
I don't know
$ su - Password: # echo $PATH /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin
gksuis affected as well, but with
gksuthere doesn't appear to be a way to get back to the old behavior.