rust-changelog: removed now useless early conditional for NULL_REVISION Now that the underlying `RevlogEntry` returned for `NULL_REVISION` is viable, it has become pointless to check NULL_REVISION several times, even for performance: the check will be far more frequent than the benefit of bailing earlier in the rare case where the requested revision is `NULL_REVISION`. This case is covered explicitly by the first assertion of `test_data_from_rev_null`.