Description of the problem / feature request:

When running with build --remote_download_toplevel or build --remote_download_minimal, if a cache key is missing (It happens to us regularly even though we don't evict files, I have not been able to figure out a reproducer)
We get the message:
"failed due to unexpected I/O exception: Failed to fetch file with hash 'eb0c1584917af56e754ba6268479fb6312dfbca19fde95042c199748d0b86ed5' because it does not exist remotely. --experimental_remote_outputs=minimal does not work if your remote cache evicts files during builds."

It would be really helpful to get more information about what that key represents (filename, target, etc?) as our workaround generally involves making a dummy change that will re-populate the cache.

Feature requests: what underlying problem are you trying to solve with this feature?

Trying to work around the fact that bazel is unable to re-populate missing cache keys.

Bugs: what's the simplest, easiest way to reproduce this bug? Please provide a minimal example if possible.

Don't have one. But the issue is about improving the error message.

What operating system are you running Bazel on?

Linux

What's the output of bazel info release?

1.0.0rc2