I would like to suggest that Pathname#ascend  and Pathname#descend
have an inclusion-flag parameter added to them to specify if the given
path should be included in the iteration or not. The default could be
true for backward compatibility. Eg.

Pathname.new('/path/to/some/file.rb').ascend {|v| p v}
    #<Pathname:/path/to/some/file.rb>
    #<Pathname:/path/to/some>
    #<Pathname:/path/to>
    #<Pathname:/path>
    #<Pathname:/>

Pathname.new('/path/to/some/file.rb').ascend(false) {|v| p v}
    #<Pathname:/path/to/some>
    #<Pathname:/path/to>
    #<Pathname:/path>
    #<Pathname:/>

Likewise for #descend.

Thanks,
T.