Fixed #29047 -- Corrected Substr test to use expressions.
Fixed #29047 -- Corrected Substr test to use expressions.

Regression in e2d6e14662d780383e18066a3182155fb5b7747b.

frankvdp/django,timgraham/django,simonw/django,timgraham/django,schinckel/django,frankvdp/django,pauloxnet/django,auvipy/django,jpic/django,adamchainz/django,wkschwartz/django,koordinates/django,timgraham/django,MarkusH/django,takis/django,manhhomienbienthuy/django,monetate/django,felixxm/django,adamchainz/django,shaib/django,jpic/django,wkschwartz/django,rsalmaso/django,kaedroho/django,schinckel/django,atul-bhouraskar/django,solarissmoke/django,frankvdp/django,blighj/django,charettes/django,schinckel/django,georgemarshall/django,charettes/django,dsanders11/django,apollo13/django,django/django,manhhomienbienthuy/django,elena/django,claudep/django,koordinates/django,MarkusH/django,georgemarshall/django,googleinterns/django,koordinates/django,dsanders11/django,atul-bhouraskar/django,elena/django,manhhomienbienthuy/django,timgraham/django,auvipy/django,django/django,fenginx/django,pauloxnet/django,rsalmaso/django,rsalmaso/django,charettes/django,wkschwartz/django,rsalmaso/django,theo-l/django,googleinterns/django,googleinterns/django,koordinates/django,pauloxnet/django,shaib/django,blighj/django,jpic/django,kaedroho/django,takis/django,ghickman/django,monetate/django,adamchainz/django,frankvdp/django,solarissmoke/django,treyhunner/django,felixxm/django,ghickman/django,MarkusH/django,googleinterns/django,simonw/django,monetate/django,felixxm/django,claudep/django,claudep/django,treyhunner/django,pauloxnet/django,freakboy3742/django,EmadMokhtar/Django,takis/django,theo-l/django,felixxm/django,solarissmoke/django,EmadMokhtar/Django,georgemarshall/django,apollo13/django,django/django,treyhunner/django,jpic/django,shaib/django,elena/django,ghickman/django,simonw/django,wkschwartz/django,freakboy3742/django,charettes/django,schinckel/django,adamchainz/django,freakboy3742/django,apollo13/django,theo-l/django,manhhomienbienthuy/django,blighj/django,atul-bhouraskar/django,georgemarshall/django,EmadMokhtar/Django,fenginx/django,fenginx/django,claudep/django,apollo13/django,treyhunner/django,MarkusH/django,django/django,blighj/django,dsanders11/django,simonw/django,atul-bhouraskar/django,auvipy/django,fenginx/django,dsanders11/django,kaedroho/django,monetate/django,solarissmoke/django,theo-l/django,takis/django,elena/django,shaib/django,ghickman/django,auvipy/django