There are a number of pages in Review Board that aren't worth having

search engines crawl. While review requests and diffs can be useful,

interdiffs are not. While the All Review Requests page, Users page, and

Groups page are useful, the lists of review requests from a user or

group are not, since they're in All Review Requests.
The Djblets datagrid code has been updated to enable greater control

over search indexing of datagrids, enabling us to disable some search

indexing.
We now include rel="nofollow noindex" in links to interdiffs for both

diffs and file attachments, and we include a <meta> tag for disabling

indexing on the diff viewer when showing interdiffs and on the User's

and Group's review requests datagrid pages.
This of course is all optional for search engines, and the most

difficult ones (particularly AI training bots) won't respect most or any

of this, but it's at least helpful for the bots who are well-behaved.

Tested the affected pages and links and verified that they contained

the correct nofollow and noindex hints.