Re: [PATCH v7 1/2] add `config_set` API for caching config-like files

> My opinion on this:
>
> * It's low priority. I think the order of priority should be (high to
>   low)
>
>   1) Finish and get the current series into pu (we're almost there, it's
>      not time to back off and restart something new).
>
>   2) Work on the other series that uses the new API. We don't need to
>      change _all_ the uses, but we do need a few tens of them to
>      validate the fact that the new API is nice and convenient to use.
>
>   3) Get new actual features for the user (tidy up config files, give
>      error messages based on numbers).
>
>   You probably won't finish everything, so just think: if the GSoC ends
>   between 1) and 2), how serious is it? if it ends between 2) and 3),
>   how serious? If reverse the order, then the risk of having nothing
>   finished and mergeable at the end is high. If it happens, the
>   community may or may not take over and finish it ...
>
> * Still, making sure that the (file, line) is doable later without too
>   much change is good. So, if indeed, moving all code to another file is
>   required, then it may make sense to do it now to avoid code move
>   later.

>> 1. config-hash.c had to be shifted to config.c entirely.
>
> Why? I guess one reason is the use of struct cf (are there others?), but
> moving just
>
> config_hash_callback
> config_hash_add_value
> git_configset_add_file
>
> to config.c should do it. Then, config.c could use config-hash.c.