I encountered this error when building docs using cargo doc for my project. I did some digging. and managed to locate where the error originated: in config::Cache::excludes_file() it calls self.trusted_file_path() to get the path for the EXCLUDES_FILE:

https://github.com/Byron/gitoxide/blob/d3588ca4fe0364c88e42cdac24ceae548355d99d/gix/src/config/cache/access.rs#L208-L212

in trusted_file_path(), self.resvoled.path_fillter(...) returns a value of Some("") (it's actual type is Path not &str but you get the point) which cause path.interpolate(ctx) to return an Err(interpolate::Error):

https://github.com/Byron/gitoxide/blob/d3588ca4fe0364c88e42cdac24ceae548355d99d/gix/src/config/cache/access.rs#L222-L232

it turns out in my git config file, there exists an entry for core.excludesfile, but it's value is blank:

[core]
	excludesfile =

I don't remember how it came to be, I think this might be a leftover by the SourceTree GUI app.

and I'm not sure if this is expected behavior or misbehavior, but apparently libgit2 didn't treat this as an error case.

I guess another way to state question is, should path_filter() return Some("") or should it return None for an blank path?