LKGMManager: Patch manifest changes before creating test manifest.

Patch the repo manifests with any changes for manifests, and
include those changes in the versioned manifest used by the CQ slave
builders.

BUG=chromium:549844
TEST=cbuildbot/run_tests (on an external checkout)
     cbuildbot --buildbot --debug --remote -g 325606 --bootstrap-args
       '-g *242726' --test-bootstrap mixed-a-pre-cq
     cbuildbot --remote -g 325606 x86-generic-paladin
     cbuildbot --buildbot --debug --remote -g 325606
       --bootstrap-args '-g *242726' master-paladin

Change-Id: I04ac21dcf0e82190f3e101ca94673656b666ead8
Reviewed-on: https://chromium-review.googlesource.com/325606
Commit-Ready: Don Garrett <dgarrett@chromium.org>
Tested-by: Don Garrett <dgarrett@chromium.org>
Reviewed-by: Aviv Keshet <akeshet@chromium.org>
Reviewed-by: David James <davidjames@chromium.org>
3 files changed