Upgrade pyfakefs to 979a878b12a3f625abe986a2249b677e6193ae3d am: a3bcabf4b7 am: 78fdc2ac9e am: 1261801ef1 am: 9f1f3798d8 am: f1db2cd21f

Original change: https://android-review.googlesource.com/c/platform/external/python/pyfakefs/+/2726660

Change-Id: I5d286395144c422ac19f4b0c0a1b5279f14942b7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>