evalv3: "cyclic reference to field" regression when using a comprehension

[mvdan]

# With the old evaluator.
env CUE_EXPERIMENT=evalv3=0
exec cue vet -c input.cue

# With the new evaluator.
env CUE_EXPERIMENT=evalv3=1
exec cue vet -c input.cue

-- input.cue --
package p

out: people.bob.kind

people: [string]: {
	kind:  "person"
	name?: string
}

if true {
	people: bob: name: "Bob"
}

As of 870bfc2:

# With the old evaluator. (0.010s)
> env CUE_EXPERIMENT=evalv3=0
> exec cue vet -c input.cue
# With the new evaluator. (0.035s)
> env CUE_EXPERIMENT=evalv3=1
> exec cue vet -c input.cue
[stderr]
people.bob.name: cyclic reference to field bob:
    ./input.cue:10:1
[exit status 1]

Note that this appears to be a bug because:

• Removing the if true wrapping fixes the bug
• Reordering out: to be at the end of the file fixes the bug

[mvdan]

Reduced from our internal infra repo.