Bitcoin Core v0.13.0 on Windows 10 (using Debug window console in GUI)
Console commands with filename arguments cause unexpected behavior when using Windows-style backslashes in paths. For example, dumpwallet D:\Bitcoin\test.txt creates D:\Bitcointest.txt. Replacing backslashes with slashes, dumpwallet D:/Bitcoin/test.txt creates D:\Bitcoin\test.txt.
The unexpected result is more confusing because dumpwallet does not print the path/filename of the created file to the console (only a blank line).
At least a note for Windows users to specify paths with slashes in the help text would be nice. Also, the help text for dumpwallet and importwallet does not indicate that the filename argument requires a full path to work correctly in the console (i.e., there's no default working directory).