relative path not used when exporting p.a.redirector rules

rules are exported with the full path. When they are imported they won't match unless the absolute path happens to be the same.

I suspect this is because p.a.redirector actually stores them as absolute paths but not sure. Either way, exportimport should export them in a form that the imports will work.

Start by tracing how collective.exportimport exports and imports p.a.redirector rules, then compare the stored absolute paths with the paths expected during import. Done means exported rules use a path form that matches correctly after import at a different location; the issue names no files or tests to run.

Written by the indexing model from the issue text.