This reverts commit f53e46c721.
The bug was actually caused by nginx messing up the Host header when reverse-proxying since I didn't have the line `proxy_set_header Host $host;` in my nginx config for Gitea.
This fixes a very rare bug when Gitea and another AP server (confirmed to happen with Mastodon) are running on the same machine, Gitea fails to verify incoming HTTP signatures. This is because the other AP server creates the sig with the public Gitea domain as the Host. However, when Gitea receives the request, the Host header is instead localhost, so the signature verification fails. Manually changing the host header to the correct value and trying the verification again fixes the bug.
This commit ensures that if the setting.AppURL is something like "http://127.0.0.1:42567" (like in the integration tests), a trailing slash will be added after that URL.
Copied from what I wrote on #19133 discussion: Handling username case is a very tricky issue and I've already encountered a Mastodon <-> Gitea federation bug due to Gitea considering Ta180m and ta180m to be the same user while Mastodon thinks they are two different users. I think the best way forward is for Gitea to only use the original case version of the username for federation so other AP software don't get confused.
Anthony Wang