For single-file revisions, with no directory except the root directory.

Manifest (you only need this to compute the $manifest_hash field
in the revision).
-----------------------------------------------
format_version "1"

dir ""

   file "$filename"
content [$newfile_id]
-----------------------------------------------

Revision
-----------------------------------------------
format_version "1"

new_manifest [$manifest_id]

old_revision [$oldrev]

patch "$filename"
 from [$oldfile_id]
   to [$newfile_id]
------------------------------------------------

The interesting packets are:

[rdata $revision_id]
<base64(gzip($revision_data))>
[end]


[fdata $newfile_id]
<base64(gzip($newfile_data))>
[end]




$<x>_id is sha1($<x>_data)

The input parameters are $filename, $oldrev (the parent for this revision),
$oldfile_id (the version of the file in $oldrev), and $newfile_data (the new version
that you're committing).