Matlab does not allow for function definitions within the code. When defined in an extra function file (eg. 'A.m') it updates correctly as octave.

In slight modification, with ~a/A.m and ~/b/A.m returning pi and e, resp., both ML and octave display pi when executing

addpath ~/a
fun = @A ;
disp(feval(fun)) ;
rmpath ~/a

addpath ~/b
disp(feval(fun)) ;

The code

function y = A()
   y = pi ;
end

fun = @A ;

function y = A()
   y = e ;
end

disp(feval(@A)) ;
disp(feval(fun)) ;

shows that the second call to feval does actually not call the updated function 'A'.

When defining 'A' in a function file 'A.m' and doing the updating there everything works, so I'm not sure if this is really a bug.