Backport #28848 by @brechtvl
When LFS hooks are present in gitea-repositories, operations like git
push for creating a pull request fail. These repositories are not meant
to include LFS files or git push them, that is handled separately. And
so they should not have LFS hooks.
Installing git-lfs on some systems (like Debian Linux) will
automatically set up /etc/gitconfig to create LFS hooks in repositories.
For most git commands in Gitea this is not a problem, either because
they run on a temporary clone or the git command does not create LFS
hooks.
But one case where this happens is git archive for creating repository
archives. To fix that, add a GIT_CONFIG_NOSYSTEM=1 to disable using the
system configuration for that command.
According to a comment, GIT_CONFIG_NOSYSTEM is not used for all git
commands because the system configuration can be intentionally set up
for Gitea to use.
Resolves#19810, #21148
Co-authored-by: Brecht Van Lommel <brecht@blender.org>
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