resolveWorkspaceRoot function
The workspace: the nearest ancestor of from holding a
buildkit_master.yaml, which is what makes it the workspace.
Implementation
String resolveWorkspaceRoot(String from) {
final root = findWorkspaceRootOrNull(from);
if (root == null) {
throw StateError('no $kBuildkitMasterYaml above $from');
}
return root;
}