Comment 54 for bug 1913421

An update on test #2 adding it to the description.

This sub-test is only in Focal and Hirsute, was not present in Bionic.
This should have preference over the other dirs (usual load as well as fallback path), therefore we do NOT remove the usual paths and check if it works, we keep them but check the loaded binary.
TL;DR Copy the .so to another place and load it from there:
 $ sudo cp /usr/lib/x86_64-linux-gnu/qemu/block-curl.so /tmp/
 $ QEMU_MODULE_DIR="/tmp/" qemu-system-x86_64 -nographic -cdrom https://cdimage.ubuntu.com/ubuntu-server/daily-live/current/impish-live-server-amd64.is
 # Then in other console check if it loaded that
 $ $ sudo cat /proc/$(pidof qemu-system-x86_64)/maps | grep curl | grep r-xp
7f3ef7dc1000-7f3ef7e23000 r-xp 0000c000 fc:01 5481 /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.6.0
7f3efa729000-7f3efa72c000 r-xp 00002000 fc:01 1086 /tmp/block-curl.so

We see the qemu block lib from the wanted path and other libs from the system as usual.