About once a week, I get an email in my mailbox that reads like this:

Hey, Kiln looks neat, but Git is totally the bee’s knees, so why the fuck are you using Mercurial?

Note that these emails are rarely (if ever) actually interested in why Kiln chose Mercurial; what they’re instead interested in is trying to piss me off enough that I get into a flamewar about why Mercurial is going to bring about Nirvana while Git causes people to eat babies using nothing but A1 sauce and a spork.

This is stupid.

Mercurial and Git are both DAG-based DVCSes. They use the same patch format. They both handle directories implicitly. They both can autodetect file deletions and renames. They both run on just about every platform I can think of. They both do a bunch of “cool” stuff, like rebasing, editing history, signing changesets, and serving as the inspiration for Ferris Bueller. They both have nearly identical performance characteristics, they both have social code sharing sites, they both are used by really big projects, they both have really good documentation, and they both got compared to James Bond or MacGyver or something like that in an analogy I didn’t really follow.

So why is there so much hating? I think what’s going on is that people are coming to these tools from Subversion or CVS, have their massive epiphany on how totally awesome DVCSes are, and then assume that only their tool can have this level of awesome, so they begin evangelizing. The problem, of course, is that the other guy feels the same way, and is also evangelizing, so the Git and the Mercurial guy end up in a locker-room-style temper-tantrum over whose tool has the best performance or whatnot, instead of how much more awesome their tools are than the competition.

This has to stop.

Mercurial’s enemy is not Git. Git’s enemy is not Mercurial.

Their enemy is Subversion.

For example, take a look at this tripe. Anyone who has seriously used Mercurial or Git for any length of time is going to spend most of the video alternating between laughing, peeing their pants, and trying to explain that they merely spilled a bunch of water on their crotch, honest. While there’s some truth to the video—a lot of people do ditch Subversion for off-line commits or for shelving or the like—the video also totally misses why people love and stay with DVCSes, which is that they make branching and merging actually work like they’re supposed to, and make source control so fast and seamless that you find you’re suddenly using it for everything.

But if you show that video to a Subversion user, they’re going to nod. And there’s really no reason for them not to: if you don’t grok what the DAG gives you, if you’ve never kicked an entire branch back-and-forth across a LAN, if you’ve never used a site like Bitbucket or GitHub, then the only tangible benefits you see from DVCSes are…well, partial commits, and the fact that their “checkouts” aren’t littered with .svn directories all over the place. And these are problems that Subversion’s upcoming versions actually might solve.

So it’s time to focus on the real enemy: the holdouts still using centralized systems. The way I see it, there are three parts to this:

1. Git and Mercurial need to do a better job handling one thing that Subversion is still better at: binary files. I know there are Git projects that are working on improving the transfer and storage of binary files within Git’s existing repository format, such as git-bigfiles. Mercurial is taking a slightly different tack through projects such as bfiles, which aim to deliberately move large binaries out of the store. We need to improve these workflows so that “DVCSes are totally better, unless” becomes simply “DVCSes are totally better.” (For our part, Fog Creek is helping fund development of bfiles via UCOSP, a semester-long student project.)
2. Git and Mercurial advocates need to remember that they need to be converting Subversion, CVS, and Perforce users, not each other. The fundamental evil here is centralized, branchless version control systems that effectively encourage all development to occur in trunk, and which make propagating bug fixes and features properly borderline impossible for all but the most disciplined shops.
3. Git and Mercurial advocates need to remember that anyone going to either system is a win for the both communities. It’s easy, in the yin/yang of Hacker News and proggit, to forget that most developers are not even aware of what DVCSes are or what they do. Yeah. Sounds crazy, I know, but trust me on this. The goal right now, if you honestly believe that the DVCS workflow is better—and I do—should be to get the mindset out there, to make more people aware of what DVCSes have to offer and why they should be using them. I for one definitely do not care whether you end up deciding that Mercurial is better than Git for you or not (well, I kind of do, because I want you to use Kiln, but otherwise…), but I get a warm fuzzy feeling knowing that, if I ever have to work with your code, I’ll be able to use a sane version control tool.

So let’s do it. No more fighting. Git, I hereby acknowledge you rock. And Mercurial, you rock so much I helped build an entire product around you. You’re both awesome. So you two shake hands…very nice. Now, see that other dude over there? The one with no real tagging or branching support?

Let’s get him.