remove misleading line in FormalSums

[mantepse]

As discussed in ​this sage-devel discussion, the "elif" branch in this excerpt can never be visited, since if its condition was satisfied, the "if" condition would have been too, and the method would have ended with the "return" statement in the "if" branch.

class FormalSums(UniqueRepresentation, Module):

    Element = FormalSum

    def _element_constructor_(self, x, check=True, reduce=True):

        if isinstance(x, FormalSum):
            P = x.parent()
            if P is self:
                return x
            elif P == self:
                return self.element_class(x._data, check=False, reduce=False, parent=self)
            else:
                x = x._data

We therefore remove the "elif" branch which can only cause confusion.

[dkrenn]

LGTM

---

New commits:

​fc1a04f

remove confusing line

[slelievre]

Can you summarize in one line in the ticket description what this ticket is about? Why was the line misleading, why removing it is making Sage better?

[mantepse]

See this thread on sage-devel:

​https://groups.google.com/forum/#!topic/sage-devel/09Xf1_coMOc