rebase: small refactoring to allow better extensibility from extensions Inhibit, one of evolve's extension, would like to change the way rebase works with obsolete changesets. During a rebase with inhibit, the inhibition of the obsolescence markers should be lifted for the rebase. With this small refactoring, inhibit and can wrap the _filterobsoleterevs function to lift inhibition cleanly and at the same time this change makes rebases' code more legible.