bpo-30394: Fix a socket leak in smtplib.SMTP.__init__() (#1700) (#1788)

Author: matrixise

Lib/smtplib.py

@@ -255,6 +255,7 @@ def __init__(self, host='', port=0, local_hostname=None,
         if host:
             (code, msg) = self.connect(host, port)
             if code != 220:
+                self.close()
                 raise SMTPConnectError(code, msg)
         if local_hostname is not None:
             self.local_hostname = local_hostname