Fix (Flux)HelmRelease cluster lookups
Fix (Flux)HelmRelease cluster lookups

The value obtained by `_, value := range slice` is overwritten on
every iteration. Thus, saving a pointer to `value` is dangerous
since its content will be overwritten in the next iteration.

From https://golang.org/ref/spec#For_range :

> For each entry it assigns iteration values to corresponding
> iteration variables if present and then executes the block.

But the iteration variables are the same on each iteration.

More explicitly, from [the gccgo source code](https://github.com/golang/gofrontend/blob/e387439bfd24d5e142874b8e68e7039f74c744d7/go/statements.cc#L5593-L5604):

```
  // The loop we generate:
  //   len_temp := len(range)
  //   range_temp := range
  //   for index_temp = 0; index_temp < len_temp; index_temp++ {
  //           value_temp = range_temp[index_temp]
  //           index = index_temp
  //           value = value_temp
  //           original body
  //   }
```

weaveworks/flux,weaveworks/flux