This appears to have broke in I0428fead7a9d1f1dc5d6aa9efc3d81ecbe6b5c64
The computation to get the comment thread used to pass the range object,
but stopped doing so in the above change. This change adds it back in
and also separates the range string computation so that additional
unit tests can be added.
Bug: Issue 7081
Change-Id: I846d0c24b894fa0577f4fefaf8dcf4fc751daa15