Dependency graph: ignore writes which do not change the state?

Given:
```
bool state

cmd void A() {
state = true
}

cmd void B() {
state = true
}

cmd void C() {
_ = state
}
```
and a trace `A, B, C`, the dependencies of C will be B.

Yet the when building the dependency graph, we could detect that the write in B does not change the state, and thus "ignore" this write, which would lead to the dependencies of C being A.