Doc tests: extra /head in links

[Warren Block]

On https://jenkins.freebsd.org/job/FreeBSD_DOC/1023/changes

The "Path in Repository" and "(diff)" links have a repeated "/head". 
So the first is

http://svnweb.freebsd.org/doc/head/head/en_US.ISO8859-1/books/porters-handbook/versions/chapter.xml

but should be

http://svnweb.freebsd.org/doc/head/en_US.ISO8859-1/books/porters-handbook/versions/chapter.xml

I can enter a PR for this if that is preferred.  Thanks!