Currently, the plugindir in the plugin manager is constructed as
{CMAKE_INSTALL_PREFIX}/bin/../{CMAKE_INSTALL_LIBDIR}/kicad/..., while
CMakes install uses {CMAKE_INSTALL_LIBDIR}/kicad/...
In case CMAKE_INSTALL_LIBDIR is a relative path "install" prefixes it
with CMAKE_INSTALL_PREFIX and both paths happen to match, otherwise
the constructed path ends up as e.g. "/usr/bin/../usr/lib/kicad/...".
For these cases where an absolute path is wanted CMake provides the
CMAKE_INSTALL_FULL_<dir> variants which works the same as
CMAKE_INSTALL_<dir> when used as DIRECTORY for install.
Stefan Brüns
Cirilo Bernardo