Submodule "git branch" says (HEAD detached at <incorrect-commit>)

[Julius Smith <jos@ccrma.stanford.edu>]

Greetings,

I have a repo with two branches A and B, say, and a submodule pointing
to a repo also with two branches, say C and D.  Branch A of the parent
uses branch C of the submodule, while B uses D.  My clone is in a
state (that I've seen often) where branch A's submodule directory
_appears_ to be using a commit for D when really it's a commit for C.
"git branch" in the the submodule directory says "(detached from
<commit-for-D>)" but this seems to be wrong.  I did "git diff
<commit>" in the submodule directory to show that it was the C-commit
and not the D-commit as it appeared.  Could "git branch" in the
submodule directory be referring to the commit at the time it was
first detached and not updating after a "git submodule update --init"
in the parent?

Thanks,
- Julius

-- 
Julius O. Smith III <jos@ccrma.stanford.edu>