I can confirm that in 0.9.3c on Windows if you use the main menu (File -> Export Wallet) you end up with a file which begins like this:
[
{
"type": "master_key_record_type",
"data": {
"index": -1,
"encrypted_key": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
"checksum": "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
}
},
{
"type": "property_record_type",
"data": {
"index": 1,
"key": "next_record_number",
"value": 989
}
},
Whereas if you do it using the console command wallet_export_keys and supply a file name together with a full path, you get the correct file.