non ghost assignment in ghost if-else block

[LinoTelschow]

Gobra verifies ghost if-else blocks that assign to non-ghost variables.
An example that verifies:

func foo() int {
    ghost bar := true
    var baz int
    ghost if bar {
        baz = 1
    } else {
        baz = 0
    }
    return baz
}

Configuration:
Gobra: 63ea747
silver: 7228e7144d41c91f02a70a68a93b6b3efae57d14
silicon: 22551b40509c381991a493da0108ea4c97fd602d
carbon: 4393d154a5ae24d994a0c2c578374bdd49c3a3b3
viperserver: 5907ce1744501b7949d25cc0d5356145431ab6f7