Merge "Fix nullptr access when cow reader open fails" am: 9e6005ad am: 9d1460be

Original change: https://android-review.googlesource.com/c/platform/system/core/+/2325397



Change-Id: I2b462357d94ca424798490f0fc8418b0c925535f
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>