rustdoc: broken link for logo on settings page

[dhardy]

Running cargo doc locally builds a settings.html page with the Rust project logo in the top-left corner. This logo URL and its link target seem to be hard-coded?

<a href='.//index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk.png' alt='logo' width='100'></a>

The link target index.html does not exist. (IIRC the rustdoc team made a deliberate decision not to generate this page, though personally I think it should exist since multiple crates may be documented from the same repo.)

I believe this is a change in a very recent version of the nightly compiler. Our hosted doc does not include the logo, presumably because it has not been updated since (cargo deadlinks spots the broken URL and makes the test fail).

Also see: deadlinks/cargo-deadlinks#36

[GuillaumeGomez]

Taking a look.