Log exit code of failed command am: f14f2cf9fe

Original change: https://android-review.googlesource.com/c/platform/external/vogar/+/2119231

Change-Id: Iee7035d1e248922f27ad5efb2ebbbb425d2b2352
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>