Huh. We don't have explicit owners for Gerrit, but I'll take a stab at who might know how to do this.

CC @dmitshur @toothrot ?

From looking at other Gerrit instances like https://gerrit-review.googlesource.com/q/is:mergeable, https://chromium-review.googlesource.com/q/is:mergeable, it appears that this option is not generally enabled elsewhere either.

The Go project generally follows Gerrit defaults, as features that are not enabled by default may have caveats, making enabling and supporting them challenging. A possible alternative path here is to redirect this to be a feature request for the Gerrit project. If a new release of Gerrit begins to support this kind of search query by default, the Go project and other Gerrit instances would all benefit.

I don't mean to rule out the possibility of us making an exception for this, and we can consider this, but I want to point out it's generally harder to enable optional Gerrit features and that we don't do it often.

I don't have a problem with this being redirected as a Gerrit feature request, but ultimately I'm only concerned about this being available on go-review.googlesource.com, so I feel like this issue should stay open until we decide it's not a good idea or it's deployed.