message: Extract method for recording a requested dependency
diff: @@ -900,6 +900,10 @@ impl<'r> Requirements<'r> {
  }
  }
  + fn require_dependency(&mut self, pkg: &'r str) {
  + self.deps.entry(pkg).or_insert((false, Vec::new())).0 = true;
  + }
  +
  fn add_feature(&mut self, feat: &'r str) -> CargoResult<()> {
  if feat.is_empty() { return Ok(()) }
  @@ -933,7 +937,7 @@ impl<'r> Requirements<'r> {
  }
  None => {
  // This is a dependency, mark it as explicitly requested.
  - self.deps.entry(feat).or_insert((false, Vec::new())).0 = true;
  + self.require_dependency(feat);
  }
  }
  }
  