replace shebang => null line in yum-etckeeper.py.

The yum-etckeeper.py is not executable.
But it has a shebang.  So rpmlint is warning.
So Fedora executes "sed -i -e 1d" in etcleeper.spec.
http://pkgs.fedoraproject.org/cgit/etckeeper.git/tree/etckeeper.spec
Upstream should not worry downstreams.
The etckeeper-bzr/__INIT__.py has same problem too.
So I will modify it in other patch.

	modified:   yum-etckeeper.py