TODO: right now precedence goes to the first list. Perhaps we should give
precedence to the longest list. In that case, `b` would be sorted before `a`.

-- a.cue --
a: 1
c: 2
e: 3
g: 4

-- b.cue --
b: 1 // unanchored
c: 2
e: 3
f: 4
g: 4
-- out/definition --
a: 1
b: 1
c: 2
e: 3
f: 4
g: 4
-- out/doc --
[]
[a]
[c]
[e]
[g]
[b]
[f]
-- out/value --
== Simplified
{
	a: 1
	b: 1
	c: 2
	e: 3
	f: 4
	g: 4
}
== Raw
{
	a: 1
	b: 1
	c: 2
	e: 3
	f: 4
	g: 4
}
== All
{
	a: 1
	b: 1
	c: 2
	e: 3
	f: 4
	g: 4
}