Description of problem: Address post-merge review comments for commit 69532c141be160b3fea03c1579ae4ac13018dcdf
REVIEW: https://review.gluster.org/22323 (afr: thin-arbiter read txn minor fixes) posted (#1) for review on master by Ravishankar N
REVIEW: https://review.gluster.org/22323 (afr: thin-arbiter read txn fixes) merged (#4) on master by Pranith Kumar Karampuri