remember previous conditions when narrowing and bounding

[DetachHead]

def foo(value: bool):
    if value:
        a = 1
    if value:
        print(a) # error: possibly unbound

[KotlinIsland]

Need to consider the dependencies of the condition mutating:

def foo(value: bool):
    if value:
        a = 1
    if value:
        print(a) # all good
    value = bool()
    if value:
        print(a) # error: possibly unbound

[DetachHead]

Duplicate of #103