uu_mv: Move directory onto itself should error out

[dmatos2012]

Hi,
MRE:

mkdir mydir/mydir_2

Results:
uutils:

> uutils mv mydir mydir/mydir_2
# 

And it also looks like it made mydir disappear?

GNU :

> mv mydir mydir/mydir_2
mv: cannot move 'mydir' to a subdirectory of itself, 'mydir/mydir_2/mydir'

This should be easy to fix. I am working on mv for nushell so I was thinking of fixing it myself but wanting to raise the issue regardless!