http: handle push of bundles > 2 GB again (issue3017)
It was very elegant that httpsendfile implemented __len__ like a string. It was
however also dangerous because that protocol can't handle sizes bigger than 2 GB.
Mercurial tried to work around that, but it turned out to be too easy to
introduce new errors in this area.
With this change __len__ is no longer implemented at all and the code will work
the same way for short and long posts.
(binary:application/octet-stream)