Remove redundant NULL check
Remove redundant NULL check

copy has been used before this point - so it is too late to be concerned
about a NULL pointer now.

This is OK as sstrdup() calls err() on NULL return from the underlying
strdup() call.

Raised by cppcheck.

stapelberg/i3,Airblader/i3-original,Airblader/i3-original,Airblader/i3,i3/i3,Airblader/i3-original,Airblader/i3-original,Airblader/i3,stapelberg/i3,stapelberg/i3,i3/i3,i3/i3,Airblader/i3-original,stapelberg/i3,i3/i3,Airblader/i3,Airblader/i3