new favicon sizes not added as hashed essential files.

[syphar]

I'm seeing these 404 errors:

when accessing for example the itertools docs.

I guess it's related to ESSENTIAL_FILES_VERSIONED and add-essential-files, but I couldn't make it work quickly and don't know the build-process good enough yet.

[syphar]

I created this issue so I don't forget it, and perhaps someone else with more knowledge of the build will give a hint or do it.

Otherwise I'll be coming back to this at some point

[jyn514]

@syphar I think you would add it to ESSENTIAL_FILES_VERSIONED, the same as other versioned files: #1301. You may want to wait for the discussion in #1312 to die down, though.