E.g. rust-lang/rust#149904 (comment) or rust-lang/rust#149389 (comment)
I tend to @bors r+ PRs and then don't wait for bors to actually state that it is in the merge queue.
In case a PR cannot be merged because it is still blocked, it would be nice to get a separate notifications through zulip. One of these PRs ended up not getting merged for 2 weeks as I stopped thinking about it after its approvial.