New check: URLs are not 404ing

[davelab6]

Observed behaviour

I've just seen a METADATA with this 404'ing URL:

Copyright 2018 The Bahianita Project Authors (https://github.com/Omnibus-Type/Bahiana/Bahianita)

Expected behaviour

• We should have checks to ensure that no bad URLs enter METADATA or DESC files [edit 2022-05-05: or bio.html files or GFK content files]

• In this special case of Github.com/$user/$repo/$something, we could try to see if Github.com/$user/$repo/tree/master/$something does NOT 404, and this case recommend that they use that URL. Eg, this should be https://github.com/Omnibus-Type/Bahiana/tree/master/Bahianita :)

[felipesanches]

we do have a check for that, but it seems that it only detects broken links (that do not load at all) and incorrectly accepts links that load a custom 404 webpage like this one. I will add logic to inspect and detect cases like that.

[felipesanches]

@davelab6 I did not find any pull request on the google/fonts repo or any commit on the upstream font-family repo with the problem you mentioned. And the METADATA.pb on the google/fonts master branch looks good. Can you please let me know where you saw an instance of this bad github URL?

[felipesanches]

oh! Nevermind! I have just found it on google/fonts master branch. I was looking up the wrong family directory.

[felipesanches]

there's actually no need to add logic to detect 404s on github pages. The check implementation is actually good:

But is only checks DESCRIPTION.en-us.html files. I must add a new similar check for METADATA.pb files.