[master] Merge branch 'trac2420'

diff --cc src/lib/datasrc/memory/zone_data_loader.cc
Simple merge

diff --cc src/lib/datasrc/memory/zone_data_updater.cc
Simple merge

diff --cc src/lib/datasrc/memory/zone_data_updater.h
Simple merge

diff --cc src/lib/datasrc/tests/Makefile.am
Simple merge

diff --cc src/lib/datasrc/tests/memory/memory_client_unittest.cc
Simple merge