pipelined_compilation errors with *.rmeta is not writeable (macOS)

[rejuvenile]

Flag used in .bazelrc:
common --@rules_rust//rust/settings:pipelined_compilation

Results in many errors on macOS, such as:

error: output file bazel-out/aarch64-darwin-opt-exec/bin/external/rules_rust++i2+rules_rust_ctve__utf16_iter-1.0.5/libutf16_iter-3010874732.rmeta is not writeable -- check its permissions

And indeed, it's not writable.

[rejuvenile]

Note, my build is normally distributed, so this could be a caching hydration issue.

[rejuvenile]

This might be a repeat of #3383, which could be cross-platform. The build doesn't always fail; in fact, the first build succeeds. It's only later builds which fail.