Changes:
2019-03-19 vadimsh@chromium.org [lucicfg] Add support for 'project:...' identities.
2019-03-19 vadimsh@chromium.org [lucicfg] Make luci.gitiles_poller(...) idempotent.
2019-03-19 vadimsh@chromium.org [lucicfg] Make luci.recipe(...) idempotent.
2019-03-19 vadimsh@chromium.org [lucicfg] Make graph.add_edge idempotent.
2019-03-14 vadimsh@chromium.org [lucicfg] Add module-scoped defaults for luci.(builder|recipe).
2019-03-14 vadimsh@chromium.org [lucicfg] Implement 'defaults' in lucicfg.rule(...).
2019-03-13 vadimsh@chromium.org [lucicfg] Implement the basic variant of lucicfg.rule(...).

R=tandrii@chromium.org
CC=dburger@chromium.org

Change-Id: I1f5707f9ca44199b18d6580651fc6c298c2290e4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/1531743Reviewed-by: Andrii Shyshkalov <tandrii@chromium.org>
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>