Transient ExtractCargoTomlEnvVars errors

[rejuvenile]

In my remote executor setup, I occasionally errors like:

ERROR: /private/var/tmp/_bazel_user/2fe8fca154ecc4fd4bfcc2428eaf334c/external/rules_rust++crate+crates__slog-2.7.0/BUILD.bazel:22:20: ExtractCargoTomlEnvVars external/rules_rust++crate+crates__slog-2.7.0/cargo_toml_env_vars.env [for tool] failed: (Exit 9): cargo_toml_variable_extractor failed: error executing ExtractCargoTomlEnvVars command (from target @@rules_rust++crate+crates__slog-2.7.0//:cargo_toml_env_vars)

... which disappear on rebuild. Each time, it is a different crate. This could be a bug in my remote setup, but all nodes should be identical.