I don't think its any thing to do with the focus, - it's the frame lines that are wrong, - you just move the pre-select lever, or make a mental estimation.
That lens has an engraved focussing scale, and if you set it to 1 meter, then any M body you put it on will register one meter on the rangefinder 'cause it follows the projection of the cam on the lens.
If you find this hard to believe, then consider the lens to be a 50 summicron. If you set the scale to 1 meter (or infinity), you can move it to any M body you like and the rangefinder will show 1 meter (or infinity) just the same.
The principal holds good whether it's a 50 or a 35, neither the body, nor the rangefinder care, only the viewfinder frames need to be changed.
If you put every leitz M lens on every M body with the lens on infinity, in every possible combination, all pictures will be sharp, and every rangefinder will show infinity.
The same holds for 1 meter.