Merge #12200: Bind functional test nodes to 127.0.0.1

65682da [tests] bind functional test nodes to 127.0.0.1 (Sjors Provoost)

Pull request description:

  Prevents OSX firewall allow-this-application-to-accept-inbound-connections permission popups and is generally safer.

  To test, make an arbitrary whitespace change to `src/bitcoind.cpp` and recompile. This normally resets the firewall's memory.

  Easiest way to reproduce a popup without running the test suite:

  ```sh
  src/bitcoind -regtest -bind=127.0.0.1 # No popup
  src/bitcoind -regtest # Popup
  ```

Tree-SHA512: ffa92f148a2ead2ceca978c285882979639be23eb31ad6a27aa81df9fdddba5d493719c92c09a351a81d638f6f739c351a721e42168d77ead60abe074df773d6

test/functional/test_framework/util.py

@@ -292,6 +292,7 @@ def initialize_datadir(dirname, n):
         f.write("port=" + str(p2p_port(n)) + "\n")
         f.write("rpcport=" + str(rpc_port(n)) + "\n")
         f.write("listenonion=0\n")
+        f.write("bind=127.0.0.1\n")
     return datadir
 
 def get_datadir_path(dirname, n):