message: Pass multiples --test-args to the tester
  Like --cfg, --test-args accept multiple matches, we should use it and
  avoid some unexpected behavior joinning the arguments with space.
diff: @@ -141,8 +141,8 @@ fn run_doc_tests(options: &TestOptions,
  p.arg("-L").arg(native_dep);
  }
  - if test_args.len() > 0 {
  - p.arg("--test-args").arg(&test_args.join(" "));
  + for arg in test_args {
  + p.arg("--test-args").arg(arg);
  }
  if let Some(cfgs) = compilation.cfgs.get(&package.package_id()) {
  