[build] reinstate sanity check for there only being one dependency repository in the build
[build] reinstate sanity check for there only being one dependency repository in the build

clockworkorange/grails-core,erdi/grails-core,clockworkorange/grails-core,clockworkorange/grails-core,erdi/grails-core,clockworkorange/grails-core,clockworkorange/grails-core,erdi/grails-core