Merge "Add robustness to possible empty BUILD_CONTEXT" into main am: 7e776b90

Original change: https://android-review.googlesource.com/c/platform/build/+/3403022



Change-Id: I446c1a23e8a3792696369573bd4a229c14fc5d6a
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>