I discovered yesterday that there was a Pi day... and I happened to have some interesting bug around it fixed today. Rotating the (1,0) vector of a 90 degrees angle didn't provide (0,1) but something really approaching. This tiny error was clearly visible because some borders weren't properly drawn due to some clipping problem. After quite a long time trying to understand what was going on, I finally saw that there were two constants for Pi in LibreOffice (and OpenOffice.org) code: in the tools and basegfx modules... and they had different precision. My problem came that the F_PI value in my code lying in the svx module was the one from the tools module... which is deprecated. In order to avoid that trouble later, I added an easy hack to remove the tools definitions for F_PI and friends: don't be afraid and hack it!
For the curious ones, this problem was introduced by new code for the borders drawing to handle the Calc rotated cells borders. Here are some screenshots of how the borders were drawn before and after the hack.
The code is still hanging in my personal git repositories on freedesktop.org... but not for long as I plan to integrate this work before 3.4 feature freeze..