How can I download the parent_diff of a review request using reviewboard api?

[Pablo G]

I can easily get the 'main' diff, but I could not manage to get the parent diff.

I want to download the diff and apply it to a local working directory, but without the parent diff the patch fails.

This is the scenario:

I have 2 local unpushed commits in git. I post the 2nd review with a parent_diff because the 1rst review is not yet pushed.

Thanks a lot.