Fix reading timezone files

Author: sdispater

CHANGELOG.md

@@ -6,6 +6,7 @@
 
 - Fixed `from_format()` not recognizing input strings when the specified pattern had escaped elements.
 - Fixed missing `x` token for string formatting.
+- Fixed reading timezone files.
 
 
 ## [2.0.3] - 2018-07-30

pendulum/tz/zoneinfo/reader.py

@@ -64,7 +64,7 @@ def _check_read(self, fd, nbytes):  # type: (...) -> bytes
         """
         result = fd.read(nbytes)
 
-        if not result or len(result) != nbytes:
+        if (not result and nbytes > 0) or len(result) != nbytes:
             raise InvalidZoneinfoFile(
                 "Expected {} bytes reading {}, "
                 "but got {}".format(nbytes, fd.name, len(result) if result else 0)