Adapt .gitreview defaultbranch to branch-v2.7.1

Change-Id: Id8c94565d07be3c7ce318bc101b645e3b0130019
Merge branch 'branch-v2.7.1' into master

Undo change to gitreview defaultbranch

Change-Id: I1a587d1c8b3fd10252f91650a31ab64597e5f696