git reflog write does not pick up user.name and user.email from config

Hi there!

I've been playing around with a toy project (an interactive step by step git tutorial that is just a repo) where I have been creating a reflog manually so far. I was happy to see the new `reflog write` feature and wanted to integrate it.

When comparing the results of my hand made reflog with the new `git reflog write` result I found some differences: It does not seem to pick up the "user.name" and "user.email" from the local git config.

Example:

```bash git init example && cd example git config --local user.name "C O Mitter" git config --local user.email "committer@example.com"

message="hi" oid="0000000000000000000000000000000000000000"

# Setting env vars works as expected
GIT_COMMITTER_NAME="$(git config --get user.name)" \
  GIT_COMMITTER_EMAIL="$(git config --get user.email)" \
  git reflog write "refs/test_vars" "$oid" "$oid" "$message"

# Picking up the information from the local config does not work unset GIT_COMMITTER_NAME GIT_COMMITTER_EMAIL git reflog write "refs/test_no_vars" "$oid" "$oid" "$message"

# Since setting the env variables to the config value, no diff expected # but: diff .git/logs/refs/test_* # 1c1 # < 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 Michael <michael@mycomp.local> 1759142076 +0200 hi # --- # > 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000 C O Mitter <committer@example.com> 1759142076 +0200 hi ```

Intuitively I would expect these values to be picked up from the local config instead of having to specify them in env variables. I didn't expect it to fall back to some system values, instead of git config. Is there a reason that this information is not used from the config? And if yes, could you set some config, so that it gets picked up?

Unfortunately my ability to understand C is too limited to grasp how `git_committer_info` works…

Thanks a lot for your work! Michael