Could I ask why we must keep this line?
If we keep this line, we could not get a "clear" return value of a node command.

For example, if we would like to store the return value of doing `@$(call run-node-command, pull-request-marionette-test)` in a variable in a bash script, we will get `run-node-command pull-request-marionette-test path/to/a_test.js path/to/b_test.js`.

It might be not good to reuse. How do you think?