base.py: Workaround ssh hangs on Windows

Workaround for ssh hangs sometimes when executing command remotely
on Windows (PowerShell/Win32-OpenSSH#1334).

It may hit an SSH rate limiter on the server-side network, which
will block IP addresses that have too many ssh connection requests
within a short period of time.

Author: haoxli

base.py

@@ -1091,8 +1091,11 @@ def get_backup_dir(backup_dir, rev):
                 Util.error('Could not find backup %s' % rev)
 
     @staticmethod
-    def remotify_cmd(server, cmd, extra_arg=''):
-        new_cmd = 'ssh wp@%s' % server
+    def remotify_cmd(server, cmd, disable_x11_fw=False, extra_arg=''):
+        new_cmd = 'ssh'
+        if disable_x11_fw:
+            new_cmd += ' -x'
+        new_cmd += ' wp@%s' % server
         if extra_arg:
             new_cmd += ' %s' % extra_arg
         new_cmd += ' "%s"' % cmd
@@ -1101,7 +1104,9 @@ def remotify_cmd(server, cmd, extra_arg=''):
     @staticmethod
     def check_server_backup(relative_path, rev_file):
         cmd = 'ls %s/%s/%s/%s' % (Util.LINUX_BACKUP_DIR, Util.HOST_OS, relative_path, rev_file)
-        cmd = Util.remotify_cmd(Util.BACKUP_SERVER, cmd)
+        # Disable SSH X11 forwarding on Windows to workaround SSH hangs when executing command remotely.
+        # Issue: https://github.com/PowerShell/Win32-OpenSSH/issues/1334
+        cmd = Util.remotify_cmd(Util.BACKUP_SERVER, cmd, disable_x11_fw=Util.HOST_OS == Util.WINDOWS)
         ret, _ = Util.execute(cmd, exit_on_error=False)
         if ret:
             return False