Clean up two more sha1 instances
Summary: See T547. One of these I just missed in D1000; the comment change just
makes it easier to audit use of hash functions by cleaning up "grep" output.
Test Plan: Ran isolation unit test.
Reviewers: btrahan, jungejason, nh, tuomaspelkonen, aran
Reviewed By: jungejason
CC: aran, jungejason
Differential Revision: 1124