If I check "Restrict where the polling can be run" and add a label, I see this error in the polling log:

Polling started on Mar 4, 2016 8:26:00 PM
Polling for the job bundle-builder-develop-android
Looking nodes where the poll can be run.
Looking for a node to the restricted label android-dev.
Can't find any eligible slave nodes.
Trying to poll on master node.

And the script is executed on the master.