The ```scipy.stats.mstats.scoreatpercentile``` function is **always** returning a masked array (where ```mask = False```).

This means that a cube with non-masked data is being converted, which is rather naughty, and very liable to upset unsuspecting users.

Infuriatingly, ```scipy.stats.stats.scoreatpercentile``` has a different kwargs signature, and doesn't understand ```alphap=1``` and ```betap=1``` ... :exclamation: 

How's about something along the lines of:
```
result = scipy.stats.mstats.scoreatpercentile(data, percent, **kwargs)
if not ma.isMaskedArray(data) and not ma.is_masked(result):
    result = np.asarray(result)
```