When '--all' is executed in subcrate, the command does not apply to other crates in the workspace

[taiki-e]

This is because current cargo-hack doesn't try to find the root manifest after finding the current package's manifest. (i.e., current cargo-hack always handles the current manifest as a root manifest.)

cargo-hack/src/workspace.rs

Lines 22 to 25 in aae0814

	// TODO: The current cargo-hack doesn't try to find the root manifest
	// after finding the current package's manifest.
	// https://github.com/taiki-e/cargo-hack/issues/11
	let root_dir = current_manifest.dir();

[taiki-e]

'--package' flag has the same issue.