Comment 84 for bug 1847361

Recheck - 1:2.11+dfsg-1ubuntu7.23 affected as expected.

upgrade to 1:2.11+dfsg-1ubuntu7.25 worked

On re-install/upgrade this dir is created
/var/run/qemu/_Debian_1_2.11+dfsg-1ubuntu7.25_/

After the .so files have been made unavailable it can still load the hotplug disk.
# virsh attach-device lateload curldisk.xml
Device attached successfully

And we see the fallback .so being loaded:
root@b:~# pidof qemu-system-x86_64; cat /proc/$(pidof qemu-system-x86_64)/maps | grep -e rbd -e ceph -e curl -e iscsi
15149
7f652157e000-7f65215f8000 r-xp 00000000 00:35 9991 /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.5.0
7f65215f8000-7f65217f7000 ---p 0007a000 00:35 9991 /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.5.0
7f65217f7000-7f65217fa000 r--p 00079000 00:35 9991 /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.5.0
7f65217fa000-7f65217fb000 rw-p 0007c000 00:35 9991 /usr/lib/x86_64-linux-gnu/libcurl-gnutls.so.4.5.0
7f65300db000-7f65300df000 r-xp 00000000 00:4c 200 /run/qemu/_Debian_1_2.11+dfsg-1ubuntu7.25_/block-curl.so
7f65300df000-7f65302df000 ---p 00004000 00:4c 200 /run/qemu/_Debian_1_2.11+dfsg-1ubuntu7.25_/block-curl.so
7f65302df000-7f65302e0000 r--p 00004000 00:4c 200 /run/qemu/_Debian_1_2.11+dfsg-1ubuntu7.25_/block-curl.so
7f65302e0000-7f65302e1000 rw-p 00005000 00:4c 200 /run/qemu/_Debian_1_2.11+dfsg-1ubuntu7.25_/block-curl.so

With an extra hop, but verified.