re-retreive the .dsc.
* Check SHA-256 of .dsc against hash from archive_query (ie projectb)
rather than letting dpkg-source do a signature verification.
- Closes:#737619.
+ Closes:#737619. Closes:#737625.
* Treat .dsc as bytes, just like everything else, rather than letting
HTTP::Message convert it to a Perl unicode string which the rest of
the program mishandles. Closes:#738536.