wrapped new system ssh key lookup in case file does not exist

lib/ansible/plugins/connections/paramiko_ssh.py

@@ -152,7 +152,11 @@ class Connection(ConnectionBase):
         self.keyfile = os.path.expanduser("~/.ssh/known_hosts")
 
         if C.HOST_KEY_CHECKING:
-            ssh.load_system_host_keys("/etc/ssh/ssh_known_hosts")
+            try:
+                #TODO: check if we need to look at several possible locations, possible for loop
+                ssh.load_system_host_keys("/etc/ssh/ssh_known_hosts")
+            except IOError:
+                pass # file was not found, but not required to function
             ssh.load_system_host_keys()
 
         ssh.set_missing_host_key_policy(MyAddPolicy(self._new_stdin))