IMPALA-11343: Override isOpen to avoid thrift bug

Overrides isOpen on TSSLSocket to work around THRIFT-5595.

Change-Id: Iff9dfb3aaf578a7dbcedd3ca8e1478a5ecb958c3
Reviewed-on: http://gerrit.cloudera.org:8080/18603
Tested-by: Impala Public Jenkins <impala-public-jenkins@cloudera.com>
Reviewed-by: Joe McDonnell <joemcdonnell@cloudera.com>

shell/TSSLSocketWithWildcardSAN.py

@@ -55,6 +55,10 @@ class TSSLSocketWithWildcardSAN(TSSLSocket.TSSLSocket):
                                    ca_certs=ca_certs, unix_socket=unix_socket,
                                    ssl_version=ssl.PROTOCOL_SSLv23)
 
+  # THRIFT-5595: override TSocket.isOpen because it's broken for TSSLSocket
+  def isOpen(self):
+    return self.handle is not None
+
   def _validate_cert(self):
     cert = self.handle.getpeercert()
     self.peercert = cert