My team handles this by committing to personal dev branches, then reviewing relatively small merges to mainline. If a review is in progress and you want to work

My team handles this by committing to personal dev branches, then reviewing relatively small merges to mainline. If a review is in progress and you want to work on changes that depend on the code in review, you make another dev branch from the review commit. Then you merge any changes back in after the review is done. Ordinarily this final merge is fairly painless, since you ideally won't have many code reviews that call for sweeping changes in your design. If you do, that's a sign of failure earlier in the process.