[main] Source code updates from dotnet/dotnet#489

dotnet-maestro[bot] wants to merge 2 commits into

maindotnet/cecil:mainfrom

darc-main-3d33dd74-3f6d-4fc7-8f45-054e7793ae03dotnet/cecil:darc-main-3d33dd74-3f6d-4fc7-8f45-054e7793ae03Copy head branch name to clipboard