streamclone: avoid some obscure error in a corner case I don't really know how, but I ran into this error: $ hg clone --stream ssh://user@dummy/empty-repo local-empty-repo streaming all changes abort: unable to apply stream clone: unsupported format: [255] I think you need an empty list of requirements for this to happen, which is weird, but an obscure error like this is not exactly helpful either. Since this is the result of an encoding bug anyway, just fix it. Differential Revision: https://phab.mercurial-scm.org/D12402