Don't return moments results for a forced fit
Don't return moments results for a forced fit

We can use moments to estimate initial parameters for a forced fit, but they
don't support holding one parameter fixed so they aren't a valid solution.
Previously, if the fit failed, the moments were returned instead.

bartscheers/tkp,mkuiack/tkp,bartscheers/tkp,transientskp/tkp,transientskp/tkp,mkuiack/tkp