I am using git with a simple in-memory FUSE filesystem. When I enable direct_io, I get a segfault from git_config_set_multivar_in_file_gently during git clone. I have full reproduction instructions using Go and macOS at https://github.com/josharian/gitbug. It also includes a stack trace in case anyone wants to try blind debugging. Happy to provide more info if it will help. Thanks, Josh