git remote vs. submodules

> Hello All,
> I was just reading about git remote and I started thinking to myself,
> "Gee, nothing I've read says that the remotes have to share a common
> ancestor.  I wonder what would happen if I added two independent
> repositories as remotes to a superproject?"
> 
> So I tried it in a very trivial case.  The first thing I learned was
> that I need to make the subprojects subdirectories of a top level
> .git-housing directory.  Or else, when I merge them in, everything in
> the top level of subproject1 gets mixed in with everything in the top
> level of subproject2.  So this doesn't seem to be a good solution for
> marrying arbitrary subprojects together.  But if I set up a library of
> subprojects properly, it seems like I could do this.
> 
> So now I'm wondering... has anybody else ever had thoughts along these
> lines?  Has anybody tried this?  Has anybody seen it work (or fail
> miserably)?
> 
> Why would I want to do this instead of using submodules?  I dunno.  It
> just came to mind when I started trying to understand what's really
> going on with remotes.  And I vaguely (and perhaps even correctly)
> recall there being some controversy regarding submodules when they
> were first introduced.

> On Thu, Nov 11, 2010 at 6:34 AM, Tomas Carnecky <tom@dbservice.com> wrote:
>> Are you maybe looking for a subtree merge?
>> http://www.kernel.org/pub/software/scm/git/docs/howto/using-merge-subtree.html
> 
> Yeah, that looks like it.  I never would have hit upon the read-tree
> step by myself -- I would have just laid things out with the prefix
> already embedded in the subprojects.
> 
> Hmmm... it seems to me that feeding changes back to the subprojects
> might be difficult (and that is born out by a comment at the end of
> the page you referenced.)

> On 11/11/10 3:44 PM, Patrick Doyle wrote:
>> On Thu, Nov 11, 2010 at 6:34 AM, Tomas Carnecky <tom@dbservice.com> wrote:
>>> Are you maybe looking for a subtree merge?
>>> http://www.kernel.org/pub/software/scm/git/docs/howto/using-merge-subtree.html
>>
>> Yeah, that looks like it.  I never would have hit upon the read-tree
>> step by myself -- I would have just laid things out with the prefix
>> already embedded in the subprojects.
>>
>> Hmmm... it seems to me that feeding changes back to the subprojects
>> might be difficult (and that is born out by a comment at the end of
>> the page you referenced.)
>
> https://github.com/apenwarr/git-subtree, it makes exactly that easier.