https://uberchromegw.corp.google.com/i/chromiumos.release/builders/lumpy-pre-flight-branch%20release-R50-7978.B

builds 210 and 211 fail in the same stage.

Isn't this branch dead? 
why are still updating it?

The failure happens because of an problem that was not fixed in that branch:

see 
https://bugs.chromium.org/p/chromium/issues/detail?id=568151

The AFDO stages allow for failures as long as they don't happen for more than 7 days. But this builder is now only executed only very infrequently. Only 2 times in more than 15 days.

Do we need to do something about this or is this branch dead?