Dear Maintainer,

when creating an empty byte, making a hard link and adding content to
the copy,
the files are still hard-linked. With non-empty files it works as expected.

Example:
$ cow bash
$ touch foo
$ cp -l foo bar
$ ls -l foo bar
-rw-r--r-- 2 fritsche fritsche 0 Apr 14 17:05 bar
-rw-r--r-- 2 fritsche fritsche 0 Apr 14 17:05 foo
$ echo foo >> foo
$ ls -l foo bar
-rw-r--r-- 2 fritsche fritsche 4 Apr 14 17:05 bar
-rw-r--r-- 2 fritsche fritsche 4 Apr 14 17:05 foo
$ echo foo >> foo
$ ls -l foo bar
-rw-r--r-- 1 fritsche fritsche 4 Apr 14 17:05 bar
-rw-r--r-- 1 fritsche fritsche 8 Apr 14 17:06 foo