Cloud Builds sporadically fail with error "Internal Error" (status = INTERNAL_ERROR)

[pwolfe]

No other errors are in available, and the build does not even start a log. Sifting through logs explorer with no filter also doesn't yield a smoking gun. 

Retrying the build normally fixes it, although it can happen 2-3 times subsequently.

Any ideas of how to investigate this issue? Or common causes of this phenomenon?

Couple interesting things about the build:

- It's a GitHub repo which hosts the code and cloudbuild.yaml

- It is run in a private pool. The private pool's network is peered with a private GKE cluster network via VPN tunnel, as the build does some K8 deployment.