PEBKAC or bug: unable to create path-like branch names

["Todd A. Jacobs" <nospam@codegnome.org>]

I want to create a nested feature branch, but git keeps complaining if I
nest more than one level deep:

    $ git checkout -b dev/feature/foo
    error: unable to resolve reference refs/heads/dev/feature/foo:
    Not a directory
    fatal: Failed to lock ref for update: Not a directory

Based on my reading of the manual pages, it seems like I should be able
to nest branch names as long as it conforms to certain rules. I read
git-branch(1), which points me to git-check-ref-format(1), which seems
to say that the rules are being followed.

On the other hand, running:

    $ git check-ref-format foo; echo $?

always results in a non-zero error code, even with a literal 'foo' as a
branch name, so clearly it isn't saying what I think it's saying.
*shrug*

Can someone provide a little clarity here?

-- 
"Oh, look: rocks!"
	-- Doctor Who, "Destiny of the Daleks"