borgbackup not working

borgbackup does not work at the moment.
There seems to be a problem between borg and the py3-msgpack version.
All dependencies are installed.
Tried on multiple Machines.

@:/# borg
Traceback (most recent call last):
File “/usr/lib/python3.6/site-packages/pkg_resources/init.py”, line 659, in _build_master
ws.require(requires)
File “/usr/lib/python3.6/site-packages/pkg_resources/init.py”, line 967, in require
needed = self.resolve(parse_requirements(requirements))
File “/usr/lib/python3.6/site-packages/pkg_resources/init.py”, line 858, in resolve
raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.ContextualVersionConflict: (msgpack-python 0.5.6 (/usr/lib/python3.6/site-packages), Requirement.parse(‘msgpack-python<0.5.0,>=0.4.6’), {’borgbackup’})

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “/usr/bin/borg”, line 6, in
from pkg_resources import load_entry_point
File “/usr/lib/python3.6/site-packages/pkg_resources/init.py”, line 3017, in
_call_aside File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3003, in _call_aside f(*args, **kwargs) File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3030, in _initialize_master_working_set working_set = WorkingSet._build_master() File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 661, in _build_master return cls._build_from_requirements(__requires__) File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 674, in _build_from_requirements dists = ws.resolve(reqs, Environment()) File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 853, in resolve raise DistributionNotFound(req, requirers) pkg_resources.DistributionNotFound: The 'msgpack-python<0.5.0,>=0.4.6' distribution was not found and is required by borgbackup

(from redmine: issue id 8893, created on 2018-05-16)