Requisition is auto approved when doing Re-Assign from BPM

Summary:

Requisition is auto approved when doing Re-Assign from BPM

Content (required):

i have created a requisition and submitted it for approval(approvers are A and B). I wanted to approve the Requisition as Admin without having to login as A or B. So, i navigated to BPM and assigned the approval sub-task(pending with Approver A) to myself using Re-Assign button and approved it. After this point, Req is pending with approver B and status shows "Pending Approval". And also new sub-task is created for the requisition pending with approver B.

Now, when i re-assigned the approver B approval sub-task to myself, i observed that Requisition status changed to "Approved" status without me having to take any approval action on the task. Can someone please let me know if this is a bug or expected.