torrc no longer accepts space in executable paths

I'm not sure exactly when this change happened but 0.3.5.8 still works with a space in the executable path while 0.4.0.2 fails to launch the executable with the same torrc file.

The following is an example torrc line that no longer works:

ClientTransportPlugin obfs2,obfs3,obfs4,scramblesuit exec C:\Program Files\obfs4proxy.exe

Is this change documented somewhere? I'd like to keep the executable path unchanged if there is a simple workaround