Phabricator and Gerrit both do a really good job of this. To me Git works fine as a pure "version control" system, but the process of collaborating on a branch

Phabricator and Gerrit both do a really good job of this. To me Git works fine as a pure "version control" system, but the process of collaborating on a branch before it gets merged into a shared branch seems to be beyond the scope of version control -- something that a higher layer tool is ideal for.