fsck: reject .gitmodules git:// urls with newlines
The previous commit taught the clone/fetch client side to reject a
git:// URL with a newline in it. Let's also catch these when fscking a
.gitmodules file, which will give an earlier warning.
Note that it would be simpler to just complain about newline in _any_
URL, but an earlier tightening for http/ftp made sure we kept allowing
newlines for unknown protocols (and this is covered in the tests). So
we'll stick to that precedent.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>