We don't need to be keeping the raw message around after it hits
git. Shard work now relies on Storable (or Sereal) and all of
the indexing code relies on the Email::MIME-like API of Eml to
access interesting parts of the message.
Similarly, smsg->{raw_bytes} is no longer carried around and we
do the CRLF adjustment when setting smsg->{bytes}.
There's also a small simplification to t/import.t while
we're in the area to use xqx instead of spawn/popen_rd.