"Don't use file dependencies outside of /usr/bin or /usr/sbin."

File deps are a nice feature, but they are very costly in terms of metadata. It'd be nice to go back to the Yum way of doing things: only pull down the list when needed. But, with the sat solver approach used by DNF (rather than yum's incremental approach), this really can only be done by moving away from these requirements in general. I don't think we're ready for this as a packaging guideline rule yet, but we can help make things prettier at first.

• In many cases, a package name can just be substituted for the filename
• In some other cases, rich (boolean OR) deps might be helpful, once those are okay
• File deps outside of /usr/bin or /usr/sbin should be looked at extra skeptically
• File deps in /bin or /sbin should be moved to corresponding /usr subdir — but only if the whole thing can't be avoided by using package deps.