> set k1 := {error("k1")}
> session save
> reload
-> k1

> set k2 := (k1 map identity).value
> session save
> reload
-> k2
$ must-mirror build.sbt build.check.1

> set k1 := {}
> session save
> reload
> k1
> k2
$ must-mirror build.sbt build.check.2

> set k1 := (k1 map {_ => sys.error("k1")}).value
> set k2 := {}
> session save
> reload
-> k1
> k2
$ must-mirror build.sbt build.check.3

> set k4 := { val x = k4.value; () }
> session save
$ must-mirror build.sbt build.check.4

> set k4 := ()
> session save
$ must-mirror build.sbt build.check.5