Depends on D19782. Ref T13217. Ref T13216. Ref T6960. We currently construct some queries by passing implode(...) directly to qsprintf().

I believe we can cover all these cases (or, at least, almost all these cases) with conversions for imploding on AND, OR, or comma. This will ultimately let us make %Q safer.

Played around with these in a toy qsprintf() script; upcoming changes will convert Phabricator callsites more aggressively.