njh/easyrdf — pull request #103 by scor (2013-01-02 12:11:17+00:00)
Title: Refactor step 2 so that an empty @vocab resets the default vocabulary

http://www.w3.org/TR/rdfa-core/#PS-default-vocabulary
"... If the value is empty, then the local default vocabulary must be reset to the Host Language defined default (if any). "

this is covered by test 0318.