Bug 433537

When using a preprocessor command, the preprocessed files seem to always be empty. On Windows 10 with Git for Windows installed, I set the PATH to include C:\Program Files\Git\usr\bin in order to have sed.exe (and cat.exe) available which are not bundled with kdiff3 anymore.
When I do a directory diff with "Full Analysis" and a "Preprocessor Command", I always get the result that all files matched and when I look at them, they are displayed as all empty (hence identical). This even happens when I use cat as the "Preprocessor Command". Obviously any more sophisticated sed filtering will also fail.
Is this a known issue with a known workaround?
(If I fail to set up the PATH, any filtering fails because sed.exe is not found.)