updateTree(baseTreeSHA, path, blobSHA, cb) {
      let newTree = {
         base_tree: baseTreeSHA, // eslint-disable-line
         tree: [{
            path: path,
            sha: blobSHA,
            mode: '100644',
            type: 'blob',
         }],
      };

      return this._request('POST', `/repos/${this.__fullname}/git/trees`, newTree, cb);
   }
Update a tree in Git
@see https://developer.github.com/v3/git/trees/#create-a-tree
@param {string} baseTreeSHA - the SHA of the tree to update
@param {string} path - the path for the new file
@param {string} blobSHA - the SHA for the blob to put at `path`
@param {Requestable.callback} cb - will receive the new tree that is created
@return {Promise} - the promise for the http request
@deprecated use {@link Repository#createTree} instead