1 head (dirname) of 'a/b/c' is 'a/b'
2 head (dirname) of 'def' is '.'
3 head (dirname) of 'a.b.c' is '.'
4 head (dirname) of 'a.b/c' is 'a.b'
5 head (dirname) of 'a' is '.'
6 head (dirname) of 'a.a' is '.'
7 head (dirname) of '.gitignore' is '.'
8 head (dirname) of 'a' is '.'
9 head (dirname) of 'a.a' is '.'