Using configuration introduced in
SOLR-3619, the following command will get locked up:
bin/solr start -f -e techproducts
Solr will start in the foreground, so the core will not be created. Then, when Solr is shutdown, the commands to create and populate the core are run and an error is thrown.
Perhaps the example creating code should cross-check for that flag and complain/abort to avoid confusion.