Variant of 26, but the point here is to show that when there's a tie
between a conjunct a pattern and one from outside a pattern, the
pattern will always win.

This is because we simplify patterns in isolation. So regardless of
the order in which we do the processing, we know that the pattern is
reachable from the result root, and it must not be made more general,
so the z: 5 from line 3 must survive. When we eventually visit b's z:
5, we find the z: 5 conjuncts from both line 1 and line 3, but we know
(either already or later on) that line 3 must survive, so line 1's is
redundant.

-- a.cue --
b: w: x: y: z: 5
b: a
a: [string]: x: y: z: 5
-- out/trim-v3 --
== a.cue
b: w: _
b: a
a: [string]: x: y: z: 5
-- diff/-out/trim-v3<==>+out/trim --
diff old new
--- old
+++ new
@@ -1,4 +1,4 @@
 == a.cue
-b: w: {}
+b: w: _
 b: a
 a: [string]: x: y: z: 5
-- out/trim-v3-noshare --
== a.cue
b: w: _
b: a
a: [string]: x: y: z: 5
-- diff/-out/trim-v3-noshare<==>+out/trim --
diff old new
--- old
+++ new
@@ -1,4 +1,4 @@
 == a.cue
-b: w: {}
+b: w: _
 b: a
 a: [string]: x: y: z: 5
-- out/trim --
== a.cue
b: w: {}
b: a
a: [string]: x: y: z: 5
