How do I export the Bazaar history of a subfolder

bzr split sub_folder

bzr fast-export BRANCH > full-history.fi

bzr fast-import-filter -i subfolder full-history.fi > subfolder.fi

bzr init-repo .
bzr fast-import subfolder.fi

branch project:
.. other files..
framework/a.file
framework/b.file
framework/c.file

branch framework:
a.file
b.file
c.file

bzr init .
bzr add .
bzr commit

bzr branch . mycopy
bzr branch . myothercopy