R1:30733ca5750c

Fix searching for commits

Summary:
fix two issues. First is that the field in the query is not
correct; the other is to make indexing handle deleted repository.

Test Plan: indexed some commits and the search result looks correct.
Reviewed By: epriestley
Reviewers: epriestley, tuomaspelkonen
CC: aran, epriestley
Differential Revision: 633