unix-ffi/re: Add test for empty string match in ffi regex.

Signed-off-by: Jos Verlinde <jos_verlinde@hotmail.com>

Author: Josverl

unix-ffi/re/test_re.py

@@ -60,3 +60,6 @@
 text = "  \thello there\n  \t  how are you?"
 indents = _leading_whitespace_re.findall(text)
 assert indents == ["  \t", "  \t  "]
+
+m = re.match(r"(.)?", "")
+assert m.groups() == (None,)