As You already said above, the whole "problem" is that in mind otsutsvija (until recently) of a normal terminal and (still) normal package Manager, git clients for Windows (by the way, it would be nice if you pointed out that the question of Windows in the header of the question) contain not only the git client, but a GUI wrapper on it and a bunch more.
At the same time,
$ ls-l /var/portage/packages/dev-vcs/git-2.9.3.tbz2
-rw-r--r-- 1 root root 11M Aug 17 01:22 /var/portage/packages/dev-vcs/git-2.9.3.tbz2
$ ls-l /usr/bin/git
-rwxr-xr-x 117 root root 1.9 M Sep 6 11:48 /usr/bin/git
$ ls-l /usr/lib/libgit2.so.0.24.0
-rwxr-xr-x 1 root root 906K Aug 10 14:10 /usr/lib/libgit2.so.0.24.0
Thus, if you want
the "small" version, which only knows how to git clone and git pull
you can take libgit and make over her self-made wrapper for your favorite language.
Or, for example, take the built-in (in the new releases Windows10) Ubuntu and put native git there and use it.