Always suppress TLS error: [Errno 0] Error

PR #180 by @Safihre

CHANGES.rst

@@ -4,6 +4,9 @@ v6.5.5
 - :issue:`99` via :pr:`186': Sockets now collect statistics (bytes
   read and written) on Python 3 same as Python 2.
 
+- :cp-issue:`1618` via :pr:`180`: Ignore OpenSSL's 1.1+ Error 0
+  under any Python while wrapping a socket.
+
 v6.5.4
 ======
 
@@ -90,7 +93,7 @@ v6.3.2
 v6.3.1
 ======
 
-- :cp-issue:`1618`: Ignore OpenSSL's 1.0+ Error 0 under Python 2 while
+- :cp-issue:`1618`: Ignore OpenSSL's 1.1+ Error 0 under Python 2 while
   wrapping a socket.
 
 v6.3.0

cheroot/ssl/builtin.py

@@ -10,8 +10,6 @@
 from __future__ import absolute_import, division, print_function
 __metaclass__ = type
 
-import sys
-
 try:
     import ssl
 except ImportError:
@@ -40,9 +38,6 @@
     del socket
 
 
-IS_BELOW_PY37 = sys.version_info[:2] < (3, 7)
-
-
 def _assert_ssl_exc_contains(exc, *msgs):
     """Check whether SSL exception contains either of messages provided."""
     if len(msgs) < 1:
@@ -153,8 +148,7 @@ def wrap(self, sock):
         except generic_socket_error as exc:
             """It is unclear why exactly this happens.
 
-            It's reproducible only under Python<=3.6 with openssl>1.0
-            and stdlib ``ssl`` wrapper.
+            It's reproducible only with openssl>1.0 and stdlib ``ssl`` wrapper.
             In CherryPy it's triggered by Checker plugin, which connects
             to the app listening to the socket port in TLS mode via plain
             HTTP during startup (from the same process).
@@ -163,9 +157,8 @@ def wrap(self, sock):
             Ref: https://github.com/cherrypy/cherrypy/issues/1618
             """
             is_error0 = exc.args == (0, 'Error')
-            ssl_doesnt_handle_error0 = IS_ABOVE_OPENSSL10 and IS_BELOW_PY37
 
-            if is_error0 and ssl_doesnt_handle_error0:
+            if is_error0 and IS_ABOVE_OPENSSL10:
                 return EMPTY_RESULT
             raise
         return s, self.get_environ(s)