[Maxima] Sanitize is not fool proof (yet) .Sanitize2 seems to work as advertized.

[Richard Fateman]

Blindly substituting in  f(x):= (globalx: 'x, otherfun(z):= x, lambda([r],x)
...)  are all ways that allow the gensym to "escape" and  gets us back to
the previous situation.

The "right" solution is to recognize free and bound instances of x in the
function body. 

RJF