XDebug fails to connect because vscode-php-debug is listening on IPv6 #288

{
  // Use IntelliSense to learn about possible attributes.
  // Hover to view descriptions of existing attributes.
  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
  "version": "0.2.0",
  "configurations": [
    {
      "name": "Listen for XDebug",
      "type": "php",
      "request": "launch",
      "pathMappings": {
        "/portal": "${workspaceFolder}",
      },
      "port": 9000,
      "log": true
    },
    {
      "name": "Launch currently open script",
      "type": "php",
      "request": "launch",
      "program": "${file}",
      "cwd": "${fileDirname}",
      "port": 9000
    }
  ]
}

zend_extension=/usr/local/lib/php/extensions/no-debug-non-zts-20160303/xdebug.so
xdebug.remote_enable=1
xdebug.remote_autostart=1
xdebug.remote_connect_back=1
xdebug.remote_log=/var/log/xdebug.log
xdebug.remote_host=host.docker.internal

Log opened at 2018-08-01 02:13:59
I: Checking remote connect back address.
I: Checking header 'HTTP_X_FORWARDED_FOR'.
I: Checking header 'REMOTE_ADDR'.
I: Remote address found, connecting to 172.19.0.1:9000.
W: Creating socket for '172.19.0.1:9000', poll success, but error: Operation now in progress (29).
E: Could not connect to client. :-(
Log closed at 2018-08-01 02:13:59

<- launchResponse
Response {
  seq: 0,
  type: 'response',
  request_seq: 2,
  command: 'launch',
  success: true }

$ lsof -nP -i4TCP:9000
COMMAND     PID            USER   FD   TYPE             DEVICE SIZE/OFF NODE NAME
Code\x20H 46903 matthewscharley   28u  IPv6 0x32d841ebd93c8e67      0t0  TCP *:9000 (LISTEN)