manifest_version.py: Use None message on unpickle error
This CL fixes a bug in which errors unpickling a status file were being
saved to BuilderStatus as a string rather than as a
ValidationFailedMessage. Instead unpickle errors will be reported as a
None message.
It also adds a docstring clarifying the expected type of BuilderStatus
message.
BUG=chromium:354576
TEST=Unit tests pass.
Change-Id: Ic131f5e07bf28e21780fd928901ef5522e37fb8c
Reviewed-on: https://chromium-review.googlesource.com/191267
Reviewed-by: David James <davidjames@chromium.org>
Tested-by: Aviv Keshet <akeshet@chromium.org>
Commit-Queue: Aviv Keshet <akeshet@chromium.org>
1 file changed
