Reverted Kyle Centers mistaken patch that removed a _currentContext->valid() that was actually required.
Reverted Kyle Centers mistaken patch that removed a _currentContext->valid() that was actually required.


ghub/osg,omega-hub/osg,stmh/osg,koshman86/osg,stmh/osg,XiaoCC/osg,XiaoCC/osg,stmh/osg,omega-hub/osg,artoolkit/osg,ghub/osg,XiaoCC/osg,artoolkit/osg,koshman86/osg,XiaoCC/osg,artoolkit/osg,stmh/osg,ntoand/osg,stmh/osg,koshman86/osg,XiaoCC/osg,ghub/osg,ntoand/osg,ghub/osg,ntoand/osg,ntoand/osg,omega-hub/osg,koshman86/osg,omega-hub/osg,artoolkit/osg