[famousactress]

Devil's advocating, but I worry about solutions like this. Abstractions leak, and if abstractions like this get traction they splinter tools' abilities to do useful things. I imagine there are corner cases where git/hg dissonance is high and wonder if this leads to a situation where we all have to care about whether a backend is capable of 'full git' or 'hg-compatible git'.

There are places where this is valuable enough to be worthwhile (say.. ANSI SQL and related high-level-language database agnostic libraries). I'm not convinced source control is one of those places.

For fogcreek, they bet the farm on hg and are presumably seeing an opportunity cost to that decision that this mitigates. This makes loads of sense for them. I'm not convinced it's all that awesome for the rest of us, or for either the hg or git user bases as a whole.

[bradleyland]

Interestingly, Joel (founder of FogCreek, producer of Kiln) wrote extensively about leaky abstractions:

http://www.joelonsoftware.com/articles/LeakyAbstractions.htm...