Always re-complete help paths in HelpScanner
Always re-complete help paths in HelpScanner

This is a temporary mitigation for an issue I've been seeing with
deferred package additions. If you load the scanner early on, the
results are cached forever, requiring a manual invalidation.

I will replace this with a smarter strategy in the next commit, but for
now wanted to show my work. It turns out that this isn't actually too
bad (slow), but I can make it better.

yrro/command-t,wincent/command-t,mtimkovich/command-t,wincent/command-t,yrro/command-t,wincent/command-t,mtimkovich/command-t