See https://ci.chromium.org/ui/p/dart-internal/builders/flutter/Linux%20flutter_release_builder/888/related-builds.

There are cases where it suceeds:
https://ci.chromium.org/ui/p/dart-internal/builders/flutter/Linux%20Production%20Engine%20Drone/47199/overview

But a few failed, blocking the release build:
https://ci.chromium.org/ui/p/dart-internal/builders/flutter/Linux%20Production%20Engine%20Drone/47195/overview

The failure looks like this:

Can't find .gclient_entries
You need to run gclient sync at least once to use 'recurse'.
This is because .gclient_entries needs to exist and be up to date.

I am going to revert https://flutter.googlesource.com/recipes/+/29f64066205f53d163e0ffaa760d1b4d5a6e587e for now, but we should roll-forward with a fix when possible. I'm also wondering if we should just do this unconditionally (every bot, not just release) so we'd get a faster signal if this works or not versus waiting for a release build specifically - it looks like, when it succeeds, it takes less than 1 minute.