Dear Ollipekka:
Some of the newer Leica R-lenses that feature internal focusing, do focus beyond the infinity range. The Leica R-Elmarit 180mm 2.8 APO is an ex&le.
The reason for this is to compensate for differences in thermal expansion and contraction, that will affect some of the internal components of the lens that are involved with focusing. Because the tolerances of Leica lenses are very precise and exacting, being able to focus past infinity is a design feature that helps to deal with these situations where the lens may be used in temperature extreme climates.
Regards,
Dale