Re: [BUG] Amending a shallow clone -> orphan branch

A bit more details:

$ git clone --depth 1 --single-branch --branch master 
https://github.com/git/git
$ cd git

Here, a shallow clone is made with just 1 commit.

$ git show -s --pretty=%P HEAD

Outputs nothing; that's already a small bug.
Surely the commit has parents!

$ git cat-file -p HEAD | grep parent

OK, that's better, finally the true parents are shown.

$ >1.txt
$ git add 1.txt
$ git commit --amend

Here, the top (and only in our clone) commit is amended.

$ git cat-file -p HEAD | grep parent

Nothing! This is the bug I'm reporting: amending the commit orphaned it.

To give a bit more background: I have a heavy-weight repo which I was 
testing on different machines. Since it's heavy, I decided to shallow 
clone just 1 commit. Upon testing on some machine, I found a small bug 
and amended a fix. Then I force-pushed. I expected the branch to be amended.

Instead, what I got was an orphaned branch, disconnected from all repo's 
branches, containing all files at once! Clearly not the best thing.