Merge "snapuserd_test: Create dup of fd before passing it to cow writer" into main am: 60d8d17fbc

Original change: https://android-review.googlesource.com/c/platform/system/core/+/3164443

Change-Id: I2f42a3ecea3c680c826aad8b8e7ff277058584fc
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>