Re: [PATCH v3 5/6] grep: enable recurse-submodules to work on <tree> objects

> Teach grep to recursively search in submodules when provided with a
> <tree> object. This allows grep to search a submodule based on the state
> of the submodule that is present in a commit of the super project.
>
> When grep is provided with a <tree> object, the name of the object is
> prefixed to all output.  In order to provide uniformity of output
> between the parent and child processes the option `--parent-basename`
> has been added so that the child can preface all of it's output with the
> name of the parent's object instead of the name of the commit SHA1 of
> the submodule. This changes output from the command
> `git grep -e. -l --recurse-submodules HEAD` from:
> HEAD:file
> <commit sha1 of submodule>:sub/file
>
> to:
> HEAD:file
> HEAD:sub/file
>
> Signed-off-by: Brandon Williams <bmwill@google.com>
> ---