process: fix bug where spinner wasn't called

Apperently there is a case where calling the spinner was required after
passing a callback to nextTick(). This fixes that issue.

This is to fix an issue as mentioned by @TooTallNate in https://github.com/joyent/node/commit/86c0745a5ebd75a4a5fa69420dfde657a5e717bc#commitcomment-2664427.

A test should be included here, but it's way too late for me to figure it out.