handle contexts inside nested blocks

[Crocmagnon]

Looks like this use case isn't detected:

for {
    err := doSomething()
    if err != nil {
        ctx = context.WithValue(ctx, "key", "value")

        continue
    }

    doSomethingElse()
}

TODO:

• [x] confirm with a test case
• [x] fix

[Crocmagnon]

There's a PR with a failing test case, if someone is interested in cracking this they're welcome :)

[venkycode]

taking this up

[Crocmagnon]

Sorry @venkycode, I had some spare time today so I tackled it.