diffhelpers: handle CRLF in hunk last line without EOL

Note that diff generation code always ends last lines without newline with a
LF, so this is a tolerance.

mercurial/diffhelpers.c

@@ -22,6 +22,9 b' static void _fix_newline(PyObject *hunk,'
 	PyObject *s = PyList_GET_ITEM(hunk, hunksz-1);
 	char *l = PyString_AS_STRING(s);
 	int sz = PyString_GET_SIZE(s);
+	if (sz > 1 && l[sz-2] == '\r')
+	        /* tolerate CRLF in last line */
+	        sz -= 1;
 	int alen = PyList_Size(a);
 	int blen = PyList_Size(b);
 	char c = l[0];

tests/test-mq-eol

@@ -20,7 +20,7 b" w(' c\\r\\n')"
 w(' d\n')
 w('-e\n')
 w('\ No newline at end of file\n')
-w('+z\n')
+w('+z\r\n')
 w('\ No newline at end of file\r\n')
 EOF