Merge "Warn on `repo upload` if you're not uploading to AOSP master." am: 026eb31f80 am: fa27392f8a

Original change: https://android-review.googlesource.com/c/platform/bootable/recovery/+/1834836

Change-Id: Icd0f444c746810df4c9a1cc373eedfad1cd08d8b