Lift peculiar side effect of path indexing out of indexer

Summary:
Ref T13639. Updating the affected path table has a peculiar side effect from D19426, which is a simplification of a peculiar side effect from earlier.

Don't condition Owners behavior on path index behavior.

Test Plan: Created a revision.

Maniphest Tasks: T13639

Differential Revision: https://secure.phabricator.com/D21614