sapyb to return even if out is not None

With CIL TomographicImaging/CIL#1742 `sapyb` returns even if the output is pre-allocated

src/common/SIRF.py

@@ -480,7 +480,7 @@ def sapyb(self, a, y, b, out=None, **kwargs):
 
         if out is None:
             check_status(z.handle)
-            return z
+        return z
 
     def power(self, other, out=None):
         '''Power function for DataContainers