[yocto] git.py support for submodules

[Richard Purdie]

On Sat, 2014-05-17 at 13:19 -0700, Christopher Larson wrote:
> 
> 
> On Saturday, May 17, 2014, Chris Morgan <chmorgan at gmail.com> wrote:
>         
>         On May 17, 2014 3:58 PM, "Christopher Larson"
>         <clarson at kergoth.com> wrote:
>         >
>         >
>         >
>         > On Saturday, May 17, 2014, Chris Morgan <chmorgan at gmail.com>
>         wrote:
>         >>
>         >> Hello.
>         >>
>         >> I noticed that git.py doesn't seem to have support for
>         submodules. I worked around this in my recipe by adding a pre
>         configure step but I was wondering if a patch to add another
>         option to git.py to fetch submodules would make sense and be
>         welcomed (pending it's implementation of course).
>         >
>         >
>         >  See gitsm.py.
>         >
>         >
>         > -- 
>         > Christopher Larson
>         > clarson at kergoth dot com
>         > Founder - BitBake, OpenEmbedded, OpenZaurus
>         > Maintainer - Tslib
>         > Senior Software Engineer, Mentor Graphics
>   >
>         I couldn't actually figure out how to use it. I looked at the
>         code and wasn't sure how it war supposed to do or what it was
>         for.
>
> You use it exactly the way you use git.py - gitsm:// instead of
> git://.  It's basically git fetching plus submodule handling. I
> personally would rather see it merged into git.py, but I can see the
> reasoning. 

FWIW the reason its separate is that mirroring is not in a good state
with submodules since git is doing magic things behind the scenes that
the fetcher and its mirror infrastructure have no knowledge of. We
should probably document that somewhere though.

There are a few ways it can be fixed but its ugly and I'd prefer to have
that code isolated for now. It could easily be merged later and it needs
someone who cares about submodules to fix it up to be a first class
citizen before that can happen. 

Cheers,

Richard