Function rustdoc_tree 

fn rustdoc_tree() -> Result<PathBuf, Error>

The rustdoc output directory, read from cargo rather than assumed.

target/doc is wrong on this workspace: CARGO_TARGET_DIR points elsewhere, which is the same trap an early sketch of the docs workflow’s copy step fell into, where cp -r $CARGO_TARGET_DIR/doc read cp -r /doc because the variable was never exported.