That should be a single dot, a double dot meant "one directory up"
if you start in "C:\here", and you create a new install called "new", it will create "C:\here\new" and install it there. it then does a "cd ./$2' to fo into the "new" directory, and runs a "git branch". when done it does a "cd .." to go back to "C:\here".
So "./$2/oil" should translate to "C:\here\new\oil", which is correct.