build: don't try to get docs for non-git if we don't need to
http://bugs.activestate.com/show_bug.cgi?id=101753

(integrated from komodo (trunk) change 83366 by marky)

git-svn-id: http://svn.openkomodo.com/repos/openkomodo/trunk@14097 b87d16e7-d29f-4ee1-b5ec-817d645d335f