Description of the problem / feature request:

If generating build event file for a target which creates a file and a symlink to this file with --remote_download_minimal and the target exists in remote cache, BEP upload code will fail with ERROR: Unable to write all BEP events to file due to 'java.io.FileNotFoundException: /home/exoson/.cache/dazel/_dazel_exoson/5d75fbbb8d44bec03b8dc3734a1ad976/execroot/test_repo/bazel-out/k8-py3-fastbuild/bin/asdf_link (No such file or directory)'

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

Have symlink.bzl

def _symlink_impl(ctx):
    out = ctx.actions.declare_file(ctx.label.name)
    ctx.actions.run_shell(
        command = "echo 'test' > $@",
        arguments = [out.path],
        outputs = [out],
    )
    link = ctx.actions.declare_symlink(ctx.label.name + "_link")
    ctx.actions.symlink(
        output = link,
        target_path = out.path,
    )
    return DefaultInfo(files = depset([link, out]))

symlink = rule(
    implementation = _symlink_impl,
)

and BUILD

load("//:symlink.bzl", "symlink")

symlink(
    name = "asdf",
)

Run

# First build the target and cache everything remotely
dazel build --experimental_allow_unresolved_symlinks --remote_cache=grpc://127.0.0.1:8980 //:asdf

# Clean so the files won't exist locally anymore
dazel clean

# Run the build with --remote_download_minimal while generating a build even file.
dazel build --experimental_allow_unresolved_symlinks --remote_cache=grpc://127.0.0.1:8980 --build_event_json_file=be.json  --remote_download_minimal //:asdf

What operating system are you running Bazel on?

Ubuntu 18.04

If bazel info release returns "development version" or "(@Non-Git)", tell us how you built Bazel.

Ran the installation script built with this

git checkout master
git pull
bazel build //scripts/packages:with-jdk/install.sh

What's the output of git remote get-url origin ; git rev-parse master ; git rev-parse HEAD ?

https://github.com/bazelbuild/bazel.git
40e7636
40e7636

Have you found anything relevant by searching the web?

#6862 (comment)
#11119

Any other information, logs, or outputs that you want to share?

Seems like when using --remote_download_minimal symlinks are created while the file linked to isn't and thus BEP upload code will fail when trying to compute the digest for the symlinked file.