Fix loading of some timezones with empty posix spec

pendulum/tz/zoneinfo/reader.py

@@ -3,7 +3,7 @@
 
 from collections import namedtuple
 from struct import unpack
-from typing import List, Dict
+from typing import Dict, List, Optional
 
 from pytzdata.exceptions import TimezoneNotFound
 
@@ -200,12 +200,15 @@ def _parse_abbrs(
 
         return abbrs
 
-    def _parse_posix_tz(self, fd):  # type: (...) -> PosixTimezone
+    def _parse_posix_tz(self, fd):  # type: (...) -> Optional[PosixTimezone]
         s = fd.read().decode("utf-8")
 
         if not s.startswith("\n") or not s.endswith("\n"):
             raise InvalidZoneinfoFile('Invalid posix rule in file "{}"'.format(fd.name))
 
         s = s.strip()
 
+        if not s:
+            return
+
         return posix_spec(s)

tests/tz/test_timezones.py

@@ -1,4 +1,5 @@
 # -*- coding: utf-8 -*-
+import pytest
 
 import pendulum
 
@@ -9,8 +10,6 @@ def test_timezones():
     assert "America/Argentina/Buenos_Aires" in zones
 
 
-def test_timezones_are_loadable():
-    zones = pendulum.timezones
-
-    for zone in zones:
-        pendulum.timezone(zone)
+@pytest.mark.parametrize("zone", [zone for zone in pendulum.timezones])
+def test_timezones_are_loadable(zone):
+    pendulum.timezone(zone)