With absurdly long URIs (as potentially seen with info requests), the AUR behaves inconsistently between HTTP 1.1 and HTTP 2.

Here's a script to demonstrate the problem:

-----8<------------------
#!/bin/bash

url='https://aur.archlinux.org/rpc?v=5&type=info'

while read -r pkg; do
url+="&arg[]=$pkg"
done < <(pacman -Qq)

curl --http2 -igvso /dev/null "$url"

---------------->8-------

curl spits out:

* Empty reply from server

If you then change the --http2 to --http1.1, you'll get an actual error reply (this is what I expect):

< HTTP/1.1 414 Request-URI Too Large
< Server: nginx/1.14.0
< Date: Sat, 20 Oct 2018 14:01:09 GMT
< Content-Type: text/html
< Content-Length: 193
< Connection: close