Re: [PATCH v7 3/3] config: add conditional include

> Sometimes a set of repositories want to share configuration settings
> among themselves that are distinct from other such sets of repositories.
> A user may work on two projects, each of which have multiple
> repositories, and use one user.email for one project while using another
> for the other.
> 
> Setting $GIT_DIR/.config works, but if the penalty of forgetting to
> update $GIT_DIR/.config is high (especially when you end up cloning
> often), it may not be the best way to go. Having the settings in
> ~/.gitconfig, which would work for just one set of repositories, would
> not well in such a situation. Having separate ${HOME}s may add more
> problems than it solves.
> 
> Extend the include.path mechanism that lets a config file include
> another config file, so that the inclusion can be done only when some
> conditions hold. Then ~/.gitconfig can say "include config-project-A
> only when working on project-A" for each project A the user works on.
> 
> In this patch, the only supported grouping is based on $GIT_DIR (in
> absolute path), so you would need to group repositories by directory, or
> something like that to take advantage of it.
> 
> We already have include.path for unconditional includes. This patch goes
> with includeIf.<condition>.path to make it clearer that a condition is
> required. The new config has the same backward compatibility approach as
> include.path: older git versions that don't understand includeIf will
> simply ignore them.
> 
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  Documentation/config.txt  | 64 +++++++++++++++++++++++++++++++++
>  config.c                  | 92 +++++++++++++++++++++++++++++++++++++++++++++++
>  t/t1305-config-include.sh | 56 +++++++++++++++++++++++++++++
>  3 files changed, 212 insertions(+)
> 
> diff --git a/Documentation/config.txt b/Documentation/config.txt
> index 1fad746efd..2a41e84bab 100644
> --- a/Documentation/config.txt
> +++ b/Documentation/config.txt
> @@ -90,6 +90,59 @@ found at the location of the include directive. If the value of the
>  be relative to the configuration file in which the include directive
>  was found.  See below for examples.
>  
> +Conditional includes
> +~~~~~~~~~~~~~~~~~~~~
> +
> +You can include a config file from another conditionally by setting a
> +`includeIf.<condition>.path` variable to the name of the file to be
> +included. The variable's value is treated the same way as
> +`include.path`. `includeIf.<condition>path` supports multiple key