Description of problem: The original loudmouth for upstream is gone, but the mcabber project maintains a fork. Please consider switching to it: https://github.com/mcabber/loudmouth I can take a look of rebasing Rawhide if you like.
I updated to the new upstream release 1.5.1 and it works here with mcabber. I use it without the loudmouth-1.4.3-async_assertion.patch patch since it does not apply anymore. I can push an updated spec to master if you like.
Since Till Maas did it, and therefore loudmouth in master branch compiles from the new source, I'm closing this bug