[python3] TypeError raised running sbin/db_updater.py

[binaryflesh]

Steps to reproduce: # cd ~/cve-search-ng/sbin && python db_updater.py

Environment:

• python3: Python 3.7.5 # python3 on ubuntu 20.04 LTS
• redis-server:

Redis server v=5.0.7 
sha=00000000:0
malloc=jemalloc-5.2.1
bits=64
build=4bb25a739ba4ae96

• mongod:

db version v3.6.8
git version: 8e540c0b6db93ce994cc548f000900bdc740f80a
OpenSSL version: OpenSSL 1.1.1c  28 May 2019
allocator: tcmalloc
modules: none
build environment:
   distarch: x86_64
   target_arch: x86_64

Interpreter output:

Traceback (most recent call last):
  File "/home/binaryflesh/cve-search-ng/sbin/db_mgmt.py", line 206, in <module>
    last_modified = parse_datetime(r.headers['last-modified'], ignoretz=True)
  File "/home/binaryflesh/.local/share/virtualenvs/cve-search-ng-PEaxLL47/lib/python3.7/site-packages/dateutil/parser/_parser.py", line 1374, in parse
    return DEFAULTPARSER.parse(timestr, **kwargs)
  File "/home/binaryflesh/.local/share/virtualenvs/cve-search-ng-PEaxLL47/lib/python3.7/site-packages/dateutil/parser/_parser.py", line 646, in parse
    res, skipped_tokens = self._parse(timestr, **kwargs)
  File "/home/binaryflesh/.local/share/virtualenvs/cve-search-ng-PEaxLL47/lib/python3.7/site-packages/dateutil/parser/_parser.py", line 725, in _parse
    l = _timelex.split(timestr)         # Splits the timestr into tokens
  File "/home/binaryflesh/.local/share/virtualenvs/cve-search-ng-PEaxLL47/lib/python3.7/site-packages/dateutil/parser/_parser.py", line 207, in split
    return list(cls(s))
  File "/home/binaryflesh/.local/share/virtualenvs/cve-search-ng-PEaxLL47/lib/python3.7/site-packages/dateutil/parser/_parser.py", line 76, in __init__
    '{itype}'.format(itype=instream.__class__.__name__))
TypeError: Parser must be a string or character stream, not NoneType