[Rietveld] Support Monorail projects in BUG= lines
[Rietveld] Support Monorail projects in BUG= lines

Staged here: https://skia-codereview-staging.appspot.com/1981002/

BUG= https://monorail.googleplex.com/p/monorail/issues/detail?id=248

Review URL: https://codereview.chromium.org/1299473003

nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra,nicko96/Chrome-Infra