pitti:~ master$ node -v
v5.6.0
pitti:~ master$ node
> path.relative('/Users/a/web/b/test/mails', '/Users/a/web/b')
'../..'
> (To exit, press ^C again or type .exit)
> pitti:~ master$ node -v
v5.7.0
pitti:~ master$ node
> path.relative('/Users/a/web/b/test/mails', '/Users/a/web/b')
'../../../b'
>
Here is the output: