fitting with weights does not work

I follow the example here:
http://astropy.readthedocs.org/en/latest/modeling/index.html#simple-1-d-model-fitting
up to
```
In [54]: g = fit_g(g_init, x, y)

In [55]: g
Out[55]: <Gaussian1D(amplitude=3.0470524687449143, mean=1.2743014580861238, stddev=0.8135350264067557)>
```
Now, I add simple weights, where each point has a weight of one, so I expect the same result, but instead I find:
```
In [56]: g = fit_g(g_init, x, y, weights=np.ones_like(x))

In [57]: g
Out[57]: <Gaussian1D(amplitude=1.0037130760672641, mean=0.011945521766504107, stddev=1.004640465609317)>
```

(In practice, I have weights that are different for every point, but if "all weights are equal" does not work, then that's not going to work either.)

@embray