Merge "prevent unintended m bp2build "" when running b" am: 54dbc8c3

Original change: https://android-review.googlesource.com/c/platform/build/+/2055109



Change-Id: I654dd587a07486f03d8ab1aa761c1f972e3fada1
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>