http://bugs.winehq.org/show_bug.cgi?id=27145
--- Comment #24 from Stefan Dösinger stefandoesinger@gmx.at 2011-08-21 17:49:13 CDT --- I usually write comments in the code or explanations in the commit messages explaining the change, pretty much every other Wine developer does that too. In this case the comment above state_depthbias should give a basic explanation what this scaling does. You'll also need background information about the D3DRS_DEPTHBIAS render state and glPolygonOffset.
Posting in the proper bug report or mailing Wine-devel is preferred over contacting the developer privately. I usually ignore private messages because they make it impossible for other people to follow the discussion and development.
I'm not sure what you mean by "diff", but if you tried to figure out what changed, then "git show dbc8702e44a987b77cdf9af31b964bb27e86fa92" will show you the changes made by the patch that was identified as the cause of this regression.