message: check that viewing source works for directories
diff: @@ -558,6 +558,8 @@ mod test {
  .create().unwrap();
  let web = env.frontend();
  assert_success("/crate/regex/0.3.0/source/src/main.rs", web)?;
  + assert_success("/crate/regex/0.3.0/source", web)?;
  + assert_success("/crate/regex/0.3.0/source/src", web)?;
  assert_success("/regex/0.3.0/src/regex/main.rs", web)?;
  Ok(())
  })
  