As far as I can tell, status_should_ignore sets the ignored pointer to 1 for any path starting with "./". I do not expect the paths "file" and "./file" to give different results because they refer to the same thing. The documentation also doesn't mention any special case for "./*".

I wrote a program to illustrate this listed below.

#include <stdio.h>
#include <git2.h>
#include <git2/errors.h>

int main(int argc, char **argv)
{
	git_repository *repo = NULL;
	int status;

	status = git_repository_open(&repo, ".");

	if (status < 0) {
		fprintf(stderr, "error: %s\n", giterr_last()->message);
		return 1;
	}

	for (int i = 1; i < argc; i++) {
		char *filename = argv[i];
		int should_ignore = 0;

		status = git_status_should_ignore(&should_ignore, repo, filename);
		
		if (status < 0) {
			fprintf(stderr, "error: %s\n", giterr_last()->message);
			return 1;
		} else {
			printf("%s %s\n", should_ignore ? "ignr:\t" : "incl:\t", filename);
		}
	}

	return 0;
}

Running this in a just initialised git repository containing no .gitignore file gives the following results:

$ ./ignore ignore.c $PWD/ignore.c ./ignore.c
incl:	 ignore.c
incl:	 /Users/jacob/Code/gittest/ignore.c
ignr:	 ./ignore.c

This was tested on v0.24.2 and e3298a3 (current master) on OS X 10.12.1. Both versions were built with Homebrew.

I originally posted this as an issue for the rust wrapper around libgit2 at alexcrichton/git2-rs#164.