Fix request #5712 - Remaining Effort in Burn Down Chart does not reflect history

Change-Id: I3ebebec9ed11f166fae722234d52c7f2553b7ef8
Merge commit 'refs/changes/12/1912/4' of ssh://gerrit.tuleap.net:29418/tuleap into tuleap-stable-master

* ssh://gerrit.tuleap.net:29418/tuleap:
  Fix request #5712 - Remaining Effort in Burn Down Chart does not reflect history

Change-Id: I9315d47ff8fa7f1877a5d65fd69444084c917df1
Tuleap 6.10.99.29

Change-Id: I440037344578a4ec2292b523aba02bd43ac0c27b