message: tweak lock message
  Change the message from
  waiting for file lock on package cache lock
  to
  waiting for file lock on package cache
diff: @@ -882,7 +882,7 @@ impl Config {
  }
  None => {
  let path = ".package-cache";
  - let desc = "package cache lock";
  + let desc = "package cache";
  // First, attempt to open an exclusive lock which is in general
  // the purpose of this lock!
  