Match only the first line and match even if the line says python3.
Otherwise we end up with multiple 3s at the end after multiple
invocations of do_install on same source.
(From OE-Core rev: 144c6c7183dd2b32c65edf325038eb84683a28f8)
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>