support nil charset

noticed nil failing when dropping the 772 fix into our mail parser project

@bf4 
done!

On Sat, Nov 15, 2014 at 12:40 PM, Benjamin Fleischer <
notifications@github.com> wrote:

> In spec/mail/encoding_spec.rb:
>
> > @@ -197,13 +197,17 @@
> >
> >    if RUBY_VERSION > '1.9'
> >      describe "#pick_encoding" do
> > +      it "bicks binary for nil" do
> > +        expect(Mail::Ruby19.pick_encoding(nil)).to eq(Encoding::BINARY)
>
> typo: s/bicks/picks
>
> I don't see why you wouldn't make this test equivalent to the other expect
> { ::Encoding.find(from) }.to raise_error(TypeError). or also test picks
> binary for empty string.
>
> I don't want that to block the bugfix, but, to me, those are both
> contracted behaviors to test.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/mikel/mail/pull/831/files#r20404849>.
>