R1:ef13b0e52b46

Expose repository "importing" flag via diffusion.repository.search

Summary: See Z2352#28072. Expose this flag to allow callers to take actions after an import finishes, which is generally reasonable.

Test Plan: Ran query from console, saw `isImporting` flag in results.

Reviewers: chad

Reviewed By: chad

Differential Revision: https://secure.phabricator.com/D16247