/usr/share/cmake-3.0/Modules/FindEigen3.cmake is in libeigen3-dev 3.2.2-3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/cmake-3.0/Modules/../../cmake-2.8/Modules/FindEigen3.cmake
/usr/share/cmake-3.0/Modules/../../cmake-2.8/Modules/FindEigen3.cmake