merge --no-commit <other-branch> requires user identity

[HelgeHesse]

What did you do before the bug happened? (Steps to reproduce your issue)

1. Create 2 branches with at least one different file on each branch
2. Do not have a ~/.gitconfig
3. Execute git merge --no-commit

What did you expect to happen? (Expected behavior)
Unstaged files in the working area and a successfull result
e.g. "Automatic merge went well; stopped before committing as requested"

What happened instead? (Actual behavior)
Git throws an error:
*** Please tell me who you are. ...

What's different between what you expected and what actually happened?
I expect to not be forced to have user identity available if I use "--no-commit". I even cannot provide them with the command shown.

Anything else you want to add:
In our workflow we do not have user information available at this stage. User identity changes for every commit,
so we do not have a ~/.gitconfig
A simple solution would be to not check user identity if merge was called with "--no-commit"

[System Info]
git version:
git version 2.31.1.331.gb0c09ab879
cpu: x86_64
built from commit: b0c09ab8796fb736efa432b8e817334f3e5ee75a
sizeof-long: 8
sizeof-size_t: 8
shell-path: /bin/sh
uname: Linux 5.3.18-lp152.66-default #1 SMP Tue Mar 2 13:18:19 UTC 2021 (73933a3) x86_64
compiler info: gnuc: 7.5
libc info: glibc: 2.26
$SHELL (typically, interactive shell): /bin/bash

[chriscool]

This is not the place to report Git bugs. This repo is only about Git developer pages. Please take a look at https://git-scm.com/community which says that the Git mailing list should be used to report Git bugs. Thanks!