Hmm.. this was part of a copy from a similar module.  Seems there's a lot of modules using URIPATH, though about twice as many use TARGETURI.  

As a community contributor, it's difficult to keep track of the common option names, when modules in master vary.  

Jeffs-MacBook-Pro:metasploit-framework jeff$ grep -r "OptString.new('URIPATH" * | wc -l
      32

I'll change this in a forthcoming commit.