http://bugs.winehq.org/show_bug.cgi?id=23247
--- Comment #14 from Sven septim.dt@gmail.com 2010-06-26 14:22:59 --- Because it didn't apply cleanly, according to http://source.winehq.org/patches/
I think you didn't use git to format your patch, which is highly recommended. There are nice guides on how to do this on the following pages.
http://wiki.winehq.org/SubmittingPatches http://wiki.winehq.org/GitWine
If you want to attach the files manually, you could use something like
git format-patch --keep-subject -o out origin
And send the files you find in ./out