backupwallet always returns true even if failed.

[ExperimentsAndIdeas]

Backupwallet always returns the following JSON if backing up to an invalid location

{ "result": null, "error": null, "id": "1"}

However bitcoind reports this

ThreadRPCServer method=backupwallet error copying wallet.dat to c:\backup@#2\curdir.test - boost::filesystem::copy_file: The system cannot find the path specified: "C:\Users\Administrator\AppData\Roaming\Bitcoin\wallet.dat", "c:\backup@#2\curdir.test"

[gavinandresen]

Fixed in 0.7.2.