Backport #30843 by wxiaoguang
Reduce the context line number to 1, make "git grep" search respect the
include/exclude patter, and fix#30785
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
This module is merged from https://github.com/go-gitea/git which is a Go module to access Git through shell commands. Now it's a part of gitea's main repository for easier pull request.