Added a test case that performs a logical operation on empty nodes sequences. 
Added a test case that performs a logical operation on empty nodes sequences. 

svn path=/trunk/eXist/; revision=5454

opax/exist,dizzzz/exist,ambs/exist,wolfgangmm/exist,wshager/exist,jessealama/exist,ljo/exist,ljo/exist,eXist-db/exist,shabanovd/exist,RemiKoutcherawy/exist,windauer/exist,hungerburg/exist,kohsah/exist,olvidalo/exist,lcahlander/exist,MjAbuz/exist,windauer/exist,zwobit/exist,lcahlander/exist,RemiKoutcherawy/exist,jessealama/exist,ambs/exist,MjAbuz/exist,olvidalo/exist,jensopetersen/exist,MjAbuz/exist,patczar/exist,joewiz/exist,lcahlander/exist,dizzzz/exist,wshager/exist,kohsah/exist,wolfgangmm/exist,zwobit/exist,jessealama/exist,shabanovd/exist,ambs/exist,MjAbuz/exist,shabanovd/exist,opax/exist,opax/exist,lcahlander/exist,wolfgangmm/exist,eXist-db/exist,windauer/exist,patczar/exist,patczar/exist,dizzzz/exist,windauer/exist,adamretter/exist,lcahlander/exist,joewiz/exist,opax/exist,ljo/exist,wshager/exist,patczar/exist,joewiz/exist,zwobit/exist,adamretter/exist,RemiKoutcherawy/exist,kohsah/exist,dizzzz/exist,lcahlander/exist,ambs/exist,eXist-db/exist,joewiz/exist,jessealama/exist,jensopetersen/exist,patczar/exist,patczar/exist,shabanovd/exist,ljo/exist,zwobit/exist,jensopetersen/exist,RemiKoutcherawy/exist,eXist-db/exist,shabanovd/exist,RemiKoutcherawy/exist,hungerburg/exist,kohsah/exist,hungerburg/exist,kohsah/exist,jessealama/exist,adamretter/exist,dizzzz/exist,ambs/exist,olvidalo/exist,joewiz/exist,wolfgangmm/exist,jessealama/exist,joewiz/exist,wolfgangmm/exist,windauer/exist,eXist-db/exist,wolfgangmm/exist,ljo/exist,eXist-db/exist,olvidalo/exist,wshager/exist,adamretter/exist,dizzzz/exist,shabanovd/exist,MjAbuz/exist,wshager/exist,RemiKoutcherawy/exist,zwobit/exist,ambs/exist,olvidalo/exist,ljo/exist,jensopetersen/exist,hungerburg/exist,MjAbuz/exist,adamretter/exist,opax/exist,wshager/exist,windauer/exist,zwobit/exist,adamretter/exist,hungerburg/exist,kohsah/exist,jensopetersen/exist,jensopetersen/exist