On the master branch @ ebe4cac, the wallet_multiwallet.py test has several issues:

1. This code:

   bitcoin/test/functional/wallet_multiwallet.py

   Lines 132 to 140 in ebe4cac

   	os.mkdir(wallet_dir('no_access'))
   	os.chmod(wallet_dir('no_access'), 0)
   	try:
   	with self.nodes[0].assert_debug_log(expected_msgs=['Error scanning']):
   	walletlist = self.nodes[0].listwalletdir()['wallets']
   	finally:
   	# Need to ensure access is restored for cleanup
   	os.chmod(wallet_dir('no_access'), stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR)
   	assert_equal(sorted(map(lambda w: w['name'], walletlist)), sorted(in_wallet_dir))

   checks for the "Error scanning" message in the debug.log caused by processing the no_access directory. However, the same message can also be generated when parsing the self_walletdat_symlink directory. As a result, the current implementation is prone to producing false-positive results.

2. Parsing the self_walletdat_symlink directory with bitcoind.exe depends on how it was built. When cross-compiling, the parsing completes without system errors. On the other hand, when building natively, it raises an "unknown error" exception and logs the "Error scanning" message.

3. This code:

   bitcoin/test/functional/wallet_multiwallet.py

   Lines 132 to 139 in ebe4cac

   	os.mkdir(wallet_dir('no_access'))
   	os.chmod(wallet_dir('no_access'), 0)
   	try:
   	with self.nodes[0].assert_debug_log(expected_msgs=['Error scanning']):
   	walletlist = self.nodes[0].listwalletdir()['wallets']
   	finally:
   	# Need to ensure access is restored for cleanup
   	os.chmod(wallet_dir('no_access'), stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR)

   is not portable due to its use of os.chmod:

Note: Although Windows supports chmod(), you can only set the file’s read-only flag with it (via the stat.S_IWRITE and stat.S_IREAD constants or a corresponding integer value).