As the help file says, option /Q keeps UNSET from complaining about undefined variables, and it used to be that - without /Q - unset did complain about such variables. Apparently now it doesn't complain anymore, but it should.
Code:
C:\>type x.btm
set x=
set x
unset x
C:\>x.btm
set x=
set x
TCC: C:\temp\maxleo\x.btm [2] Not in environment "x*"
unset x
C:\>ver
TCC 14.01.33 Windows 7 [Version 6.1.7601]
C:\>