Fix VLS_NETWORK setup bug in cln:native mode

Author: ksedgwic

contrib/pyln-testing/pyln/testing/utils.py

@@ -766,7 +766,8 @@ def start(self, stdin=None, wait_for_initialized=True, stderr_redir=False):
                 BITCOIND_CONFIG['rpcport'])
 
             # The remote hsmd proxies need to know which network we are using
-            self.env['VLS_NETWORK'] = self.opts['network']
+            if 'network' in self.opts:
+                self.env['VLS_NETWORK'] = self.opts['network']
 
             self.opts['bitcoin-rpcport'] = self.rpcproxy.rpcport
             TailableProc.start(self, stdin, stdout_redir=False, stderr_redir=stderr_redir)