[automerger skipped] Fix race condition for cas sessions -- DO NOT MERGE am: c927af1287 am: ebbcb99ca1  -s ours am: c61b35c29b  -s ours am: 11f23b2478
am: 3506f424ae  -s ours

Change-Id: I81afb05d98740d5bb2717581e5c3ba51f26e9a29