The git wrapper was never fully supported and had some rough edges (I think it was only ever a 20% project, and also its, like, really old). And the customized mercurial has been around for more than 7 years, I think close to a decade (the client I'm using right now is turning 7, and it wasn't my first one).
I used git5 from when I started in 2011 to when I left in 2017.
I'm going back starting on monday, so I'm curious to try out jj.
In the past 10 years it's all been github and gitlab, and their code review tools are so painful, specifically w.r.t. tracking discussions across revisions. I never felt excited to try out jj because I was afraid it would that situation even worse.
I started using git as my daily driver at Google in 2018. I was forcibly kicked off it for mercurial in 2020. The deprecation plan for mercurial is 2026 IIUC. Maybe if you adopted mercurial early it's different.
Why did Google decide to choose Mercurial? Based on what I read the main reason was that the mercurial dev team was willing to prioritize features needed for Google to add custom extensions to support its monorepo, and the git dev team wasn't going to reprioritize just for the sake of Google.
Yes, that's correct. Another reason was that Mercurial is easier to customize because it's written in Python so we could sometimes just replace whatever we needed without needing much changes from Mercurial itself.
Yet another reason is that the .git directory is considered a documented API and several other tools and libraries depend on it (e.g. JGit and libgit2). So any new features for Google would need to be made to those tools too if we wanted things built on them to work.
I can second that the aforementioned reasons are true. The funny difference is that Google employs the primary git maintainer. Git has a lot of customers though so it rightfully is very conservative with development.
The git wrapper was never fully supported and had some rough edges (I think it was only ever a 20% project, and also its, like, really old). And the customized mercurial has been around for more than 7 years, I think close to a decade (the client I'm using right now is turning 7, and it wasn't my first one).