message: Accept more underscore variants in configuration
  Preserving more historical behavior of the old TOML parser.
diff: @@ -228,8 +228,12 @@ pub struct TomlManifest {
  dependencies: Option<HashMap<String, TomlDependency>>,
  #[serde(rename = "dev-dependencies")]
  dev_dependencies: Option<HashMap<String, TomlDependency>>,
  + #[serde(rename = "dev_dependencies")]
  + dev_dependencies2: Option<HashMap<String, TomlDependency>>,
  #[serde(rename = "build-dependencies")]
  build_dependencies: Option<HashMap<String, TomlDependency>>,
  + #[serde(rename = "build_dependencies")]
  + build_dependencies2: Option<HashMap<String, TomlDependency>>,
  features: Option<HashMap<String, Vec<String>>>,
  target: Option<HashMap<String, TomlPlatform>>,
  replace: Option<HashMap<String, TomlDependency>>,
  @@ -630,19 +634,23 @@ impl TomlManifest {
  // Collect the deps
  process_dependencies(&mut cx, self.dependencies.as_ref(),
  None)?;
  - process_dependencies(&mut cx, self.dev_dependencies.as_ref(),
  - Some(Kind::Development))?;
  - process_dependencies(&mut cx, self.build_dependencies.as_ref(),
  - Some(Kind::Build))?;
  + let dev_deps = self.dev_dependencies.as_ref()
  + .or(self.dev_dependencies2.as_ref());
  + process_dependencies(&mut cx, dev_deps, Some(Kind::Development))?;
  + let build_deps = self.build_dependencies.as_ref()
  + .or(self.build_dependencies2.as_ref());
  + process_dependencies(&mut cx, build_deps, Some(Kind::Build))?;
  for (name, platform) in self.target.iter().flat_map(|t| t) {
  cx.platform = Some(name.parse()?);
  process_dependencies(&mut cx, platform.dependencies.as_ref(),
  None)?;
  - process_dependencies(&mut cx, platform.build_dependencies.as_ref(),
  - Some(Kind::Build))?;
  - process_dependencies(&mut cx, platform.dev_dependencies.as_ref(),
  - Some(Kind::Development))?;
  + let build_deps = platform.build_dependencies.as_ref()
  + .or(platform.build_dependencies2.as_ref());
  + process_dependencies(&mut cx, build_deps, Some(Kind::Build))?;
  + let dev_deps = platform.dev_dependencies.as_ref()
  + .or(platform.dev_dependencies2.as_ref());
  + process_dependencies(&mut cx, dev_deps, Some(Kind::Development))?;
  }
  replace = self.replace(&mut cx)?;
  @@ -998,8 +1006,12 @@ struct TomlPlatform {
  dependencies: Option<HashMap<String, TomlDependency>>,
  #[serde(rename = "build-dependencies")]
  build_dependencies: Option<HashMap<String, TomlDependency>>,
  + #[serde(rename = "build_dependencies")]
  + build_dependencies2: Option<HashMap<String, TomlDependency>>,
  #[serde(rename = "dev-dependencies")]
  dev_dependencies: Option<HashMap<String, TomlDependency>>,
  + #[serde(rename = "dev_dependencies")]
  + dev_dependencies2: Option<HashMap<String, TomlDependency>>,
  }
  impl TomlTarget {
  