Add corner case tests for diff-index and diff-files

diff --git a/merge-index.c b/merge-index.c
index bbb700b54eab2a14f60e090231a196874ff3a9e0..7491c56ad25332fb4aae6a075bf0577a1d800c3b 100644 (file)
--- a/merge-index.c
+++ b/merge-index.c
@@ -91,7 +91,7 @@ int main(int argc, char **argv)
        signal(SIGCHLD, SIG_DFL);
 
        if (argc < 3)
-               usage("git-merge-index [-o] [-q] <merge-program> (-a | <filename>*)");
+               usage("git-merge-index [-o] [-q] <merge-program> (-a | [--] <filename>*)");
 
        setup_git_directory();
        read_cache();