Code review comment for lp:~jelmer/bzr/export-use-tree-timestamp

 review: needsfixing

perhaps per_file_timestamps - the source is the tree, but its the
lookup-per-rev that will hurt.

Crucially the docstring change should be a little more verbose about
this, so that folk reading it can predict the behaviour/tradeoff.

Should this be exposed in 'bzr export's command line?

Cheers,
Rob