Description of problem:
Every time radicale is started, it crashes immediately.

Version-Release number of selected component:
radicale-2.1.9-2.fc28

Additional info:
reporter:       libreport-2.9.5
cmdline:        /usr/bin/python3 /usr/bin/radicale --daemon --pid=/var/run/radicale/radicale.pid
crash_function: resolve
exception_type: pkg_resources.ContextualVersionConflict
executable:     /usr/bin/radicale
interpreter:    python3-3.6.5-1.fc28.x86_64
kernel:         4.16.11-300.fc28.x86_64
runlevel:       N 5
type:           Python3

Truncated backtrace:
__init__.py:774:resolve:pkg_resources.DistributionNotFound: The 'vobject==0.9.5' distribution was not found and is required by Radicale

Traceback (most recent call last):
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 570, in _build_master
    ws.require(__requires__)
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 888, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 779, in resolve
    raise VersionConflict(dist, req).with_context(dependent_req)
pkg_resources.ContextualVersionConflict: (vobject 0.9.4.1 (/usr/lib/python3.6/site-packages), Requirement.parse('vobject==0.9.5'), {'Radicale'})

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/bin/radicale", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3095, in <module>
    @_call_aside
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3079, in _call_aside
    f(*args, **kwargs)
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 3108, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 572, in _build_master
    return cls._build_from_requirements(__requires__)
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 585, in _build_from_requirements
    dists = ws.resolve(reqs, Environment())
  File "/usr/lib/python3.6/site-packages/pkg_resources/__init__.py", line 774, in resolve
    raise DistributionNotFound(req, requirers)
pkg_resources.DistributionNotFound: The 'vobject==0.9.5' distribution was not found and is required by Radicale

Local variables in innermost frame:
new_requirement: Requirement.parse('six>=1.5')
new_requirements: [Requirement.parse('six>=1.5')]
requirers: {'Radicale'}
ws: <pkg_resources.WorkingSet object at 0x7f2b7a3b08d0>
dist: None
req: Requirement.parse('vobject==0.9.5')
required_by: defaultdict(<class 'set'>, {Requirement.parse('python-dateutil==2.6.1'): {'Radicale'}, Requirement.parse('vobject==0.9.5'): {'Radicale'}, Requirement.parse('six>=1.5'): {'python-dateutil'}})
req_extras: {Requirement.parse('python-dateutil==2.6.1'): (), Requirement.parse('vobject==0.9.5'): (), Requirement.parse('six>=1.5'): ()}
to_activate: [Radicale 2.1.9 (/usr/lib/python3.6/site-packages), python-dateutil 2.6.1 (/usr/lib/python3.6/site-packages)]
best: {'radicale': Radicale 2.1.9 (/usr/lib/python3.6/site-packages), 'python-dateutil': python-dateutil 2.6.1 (/usr/lib/python3.6/site-packages), 'vobject': None}
processed: {Requirement.parse('Radicale==2.1.9'): True, Requirement.parse('python-dateutil==2.6.1'): True}
extras: None
replace_conflicting: False
installer: None
env: <pkg_resources.Environment object at 0x7f2b7a3fb550>
requirements: [Requirement.parse('six>=1.5')]
self: <pkg_resources.WorkingSet object at 0x7f2b7a3b08d0>