`bash` would fork a new shell without the defined wp alias function

there should be no need to check `dirname $0` since the provision script already run each `vvv-init.sh` from its dirname, so it can use `pwd` 

Anyway this was intended to be backward-compatible so if this create problems we can think to make it work another way that allows forking a new shell for each custom script, such as defining the alias function for all root shells, but there are downsides i.e. it would not raise a warning if the user is actually using root to do stuff outside the provision