Description of problem:
=======================
Remove-brick: File is not migrated from the decommissioned bricks,  commit results in data loss

Version-Release number of selected component (if applicable):
3.8.4-5.el7rhgs.x86_64

Steps to Reproduce:
===================
1) Create a distributed-replicate volume and start it.
2) FUSE mount the volume on multiple clients.
3) Run the below tasks from the clients,
  a) Client-1: Create a big file usind dd command
     dd if=/dev/urandom of=BIG bs=1024k count=10000
  b) Client-2: continuous lookups using ls -lRT
  c) Client-3: continuous lookups using find
  d) Client-4: Start a script which creates hardlinks to the file 'BIG'
4) With Step-3 running,  Identify on which bricks the file is actually stored and remove those bricks.
5) Wait till the migration completes.

The file is still present on the decommissioned bricks. so, if we issue remove-brick commit there will be a data loss. 

Actual results:
===============
File is not migrated from the decommissioned bricks,  commit results in data loss

Expected results:
=================
File should get migrated from decommissioned bricks to other bricks which are part of volume.