undo sendall() change unrelated to the bug fix

cheroot/ssl/pyopenssl.py

@@ -146,22 +146,20 @@ def readline(self, size=-1):
         )
 
     def read(self, *args, **kwargs):
-        """Read from the wrapped socket, with retry."""
+        """Read from the wrapped socket."""
         return self._safe_call(
             True,
             super(SSLFileobjectMixin, self).read,
             *args, **kwargs
         )
 
     def sendall(self, *args, **kwargs):
-        """Send whole message to the socket. Unsupported, do not use."""
-        # Not supported due to https://github.com/pyca/pyopenssl/issues/176.
-        # Until that bug is fixed, sendall() may throw SSL.WantWriteError, but
-        # there is no correct way to retry the call because we don't know how
-        # many bytes were already transmitted. We could work around this by
-        # reimplementing sendall() using send(), but we don't actually use
-        # sendall() anywhere.
-        raise NotImplementedError('sendall() is unsupported by pyOpenSSL')
+        """Send whole message to the socket."""
+        return self._safe_call(
+            False,
+            super(SSLFileobjectMixin, self).sendall,
+            *args, **kwargs
+        )
 
     def send(self, *args, **kwargs):
         """Send some part of message to the socket."""