Regression in 0.10.2

[stanislavlevin]

With 2dd1064 the following code

import logging

from k5test import realm

logging.basicConfig(level=logging.DEBUG)
rlm = realm.K5Realm()

fails as

DEBUG:k5test.realm:Using discovered path for krb5-config (/usr/bin/krb5-config)
Traceback (most recent call last):
  File "/usr/src/test.py", line 6, in <module>
    rlm = realm.K5Realm()
  File "/usr/lib/python3/site-packages/k5test/realm.py", line 156, in __init__
    self._init_paths(**paths)
  File "/usr/lib/python3/site-packages/k5test/realm.py", line 252, in _init_paths
    value = _discover_path(name, default, paths)
  File "/usr/lib/python3/site-packages/k5test/realm.py", line 76, in _discover_path
    _LOG.debug(f"Using default path for {name} ({path}): {e}")
NameError: name 'e' is not defined