Comment # 6 on bug 924346 from Michael Andres

I suspect that one of the plugins
(/usr/lib/zypp/plugins/commit/btrfs-defrag-plugin.py
and/or /usr/lib/zypp/plugins/commit/snapper.py) cause some daemon to be
started. 

The daemon does not close it's stdout (inherited from the plugin). This way the
pipe is not closed and we hang trying to read the plugins final data. I'll
check the zypp code to make sure we're always protected against such miss
behaving deamons. The plugin code uses a slightly different code path than the
rpm-install (where miss behaving deamons launched in %pre/%post scripts dont
bit us).

If you can identify the daemon (some snapper related stuff) and kill it, zypper
should continue.