Description of problem:
running fedpkg new-sources caused it to crash.

Version-Release number of selected component:
fedpkg-1.33-1.fc28

Additional info:
reporter:       libreport-2.9.5
cmdline:        /usr/bin/python2 /usr/bin/fedpkg new-sources ./python-catkin_pkg-0.4.2.tar.gz
crash_function: resolve
exception_type: DistributionNotFound
executable:     /usr/bin/fedpkg
interpreter:    python2-2.7.15-2.fc28.x86_64
kernel:         4.16.8-300.fc28.x86_64
runlevel:       N 5
type:           Python
uid:            1000

Truncated backtrace:
__init__.py:778:resolve:DistributionNotFound: The 'rpm-py-installer' distribution was not found and is required by rpkg

Traceback (most recent call last):
  File "/usr/bin/fedpkg", line 6, in <module>
    from pkg_resources import load_entry_point
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3088, in <module>
    @_call_aside
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3072, in _call_aside
    f(*args, **kwargs)
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 3101, in _initialize_master_working_set
    working_set = WorkingSet._build_master()
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 574, in _build_master
    ws.require(__requires__)
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 892, in require
    needed = self.resolve(parse_requirements(requirements))
  File "/usr/lib/python2.7/site-packages/pkg_resources/__init__.py", line 778, in resolve
    raise DistributionNotFound(req, requirers)
DistributionNotFound: The 'rpm-py-installer' distribution was not found and is required by rpkg

Local variables in innermost frame:
replace_conflicting: False
dist: None
requirers: set(['rpkg'])
to_activate: [fedpkg 1.33 (/usr/lib/python2.7/site-packages), six 1.11.0 (/usr/lib/python2.7/site-packages), rpkg 1.54 (/usr/lib/python2.7/site-packages), python-bugzilla 2.1.0 (/usr/lib/python2.7/site-packages), openidc-client 0.5.0 (/usr/lib/python2.7/site-packages), six 1.11.0 (/usr/lib/python2.7/site-packages)]
req: Requirement.parse('rpm-py-installer')
requirements: [Requirement.parse('requests'), Requirement.parse('pycurl>=7.19'), Requirement.parse('koji>=1.15'), Requirement.parse('GitPython'), Requirement.parse('cccolutils>=1.4'), Requirement.parse('requests'), Requirement.parse('requests')]
new_requirements: []
req_extras: {Requirement.parse('six'): (), Requirement.parse('openidc-client'): (), Requirement.parse('cccolutils>=1.4'): (), Requirement.parse('koji>=1.15'): (), Requirement.parse('rpkg'): (), Requirement.parse('six>=1.9.0'): (), Requirement.parse('requests'): (), Requirement.parse('python-bugzilla'): (), Requirement.parse('pycurl>=7.19'): (), Requirement.parse('GitPython'): (), Requirement.parse('rpm-py-installer'): ()}
required_by: defaultdict(<type 'set'>, {Requirement.parse('six'): set(['fedpkg']), Requirement.parse('openidc-client'): set(['fedpkg']), Requirement.parse('cccolutils>=1.4'): set(['rpkg']), Requirement.parse('koji>=1.15'): set(['rpkg']), Requirement.parse('rpkg'): set(['fedpkg']), Requirement.parse('six>=1.9.0'): set(['rpkg']), Requirement.parse('requests'): set(['rpkg', 'python-bugzilla', 'openidc-client']), Requirement.parse('python-bugzilla'): set(['fedpkg']), Requirement.parse('pycurl>=7.19'): set(['rpkg']), Requirement.parse('GitPython'): set(['rpkg']), Requirement.parse('rpm-py-installer'): set(['rpkg'])})
extras: None
ws: <pkg_resources.WorkingSet object at 0x7f860ac71f50>
new_requirement: Requirement.parse('requests')
env: <pkg_resources.Environment object at 0x7f860ac71090>
installer: None
self: <pkg_resources.WorkingSet object at 0x7f860ac71f50>
best: {'rpm-py-installer': None}
processed: {Requirement.parse('six'): True, Requirement.parse('openidc-client'): True, Requirement.parse('rpkg'): True, Requirement.parse('six>=1.9.0'): True, Requirement.parse('fedpkg==1.33'): True, Requirement.parse('python-bugzilla'): True}