message: Passing a relative path to Workspace now bails with proper message.
  Previously, this failure will return an unhelpful warning.
  This commit adds an error message saying that the argument for
  `manifest_path` must be an absolute path.
diff: @@ -147,7 +147,10 @@ impl<'cfg> Workspace<'cfg> {
  ws.target_dir = config.target_dir()?;
  if manifest_path.is_relative() {
  - ws.root_manifest = Some(std::env::current_dir()?);
  + anyhow::bail!(
  + "manifest_path:{:?} is not an absolute path. Please provide an absolute path.",
  + manifest_path
  + )
  } else {
  ws.root_manifest = ws.find_root(manifest_path)?;
  }
  