lib/sysrev/sysrev.js
function(systemId, fileName, contents, cb) {
    var repoPath = _meta.repoPath(systemId);
    fse.writeFile(path.join(repoPath, fileName), contents, 'utf8', cb);
  }
function(systemId, fileName, contents, cb) {
    var repoPath = _meta.repoPath(systemId);
    fse.writeFile(path.join(repoPath, fileName), contents, 'utf8', cb);
  }
commit a new version of the system, the head of the commit log
may be ahead of the actual deployed version of the system