Martin Langhoff [off-list ref] writes:
GIT won't literally lose them, someone could run git-fsck and fish
out the dangling heads from the repo, and after a bit of spelunking
recover them, but it's suddenly a really tricky operation.
"git-lost-found".
You are right. We will lose #1 and #2, (although the "already
up to date" might catch some cases) and this _is_ dangerous. I
need to do something about this soon.
Thanks for the discussion.
[Footnote]
*1* ... or #1 and #3 --- sorry, my "one of them picked up by
upstream" scenario description was inconsistent in the previous
message.