[RFC] Configurable name(s) for .gitmodules

["Ping Yin" <pkufranky@gmail.com>]

I have a super project with many submodules. Each kind of role may
check out different set of submodules. There are some common modules
which are almost checked out by every role.

Here comes my question: how to implement this elegantly? If all
submodules are put in the same .gitmodules, every role has to in the
command line manually designate all submodules to be checked out.
However, it's hard to remember which submodules is required by which
role, not to mention the so huge .gitmodules. Maybe a script for each
role can help, but it's a little ugly.

If the name for '.gitmodules' is configurable, we can check in
modules.roleA and modules.roleB, etc. Then role A can designate the
corresponding modules.roleA as .gitmodules. Furtherly, if mutiple
names are allowed,  for common modules, we can have modules.common and
then submodule.defaultnames="modules.common, modules.roleA"  to avoid
duplicated module name entires in both modules.roleA and
modules.roleB.

I have gone deeply into git-submodule.sh and see
"GIT_CONFIG=.gitmodules" is used. However, configuable multiple names
can't be implemented in this way.

Recap:
1. configurable name for '.gitmodules'
2. better to allow mutiple names
3. the implementation issue for mutiple names

-- 
Ping Yin