Use unsigned version format.
This way can use one additional bit, and when encountering invalid revlogs
with the first bit set don't produce python warnings or strange error messages.
adding foo
% clone via stream
streaming all changes
XXX files to transfer, XXX bytes of data
transferred XXX bytes in XXX seconds (XXX XB/sec)
XXX files updated, XXX files merged, XXX files removed, XXX files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
% try to clone via stream, should use pull instead
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
% clone via pull
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
adding bar
% pull
changegroup: u=http://localhost:20059/
pulling from http://localhost:20059/
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
(run 'hg update' to get a working copy)