[PATCH 0 of 4] Parent Delta

[Pradeepkumar Gayam]

Hi,

I have done little bit of hacking on revlog, this patch series contains the necessary changes for the implementation of parent delta. When I run the test suit, 10 tests failed because of obvious reasons. But performance has gone down drastically . I explained why performance has gone down in wiki [0]. So, I dont bother to rewrite every again here. I am pretty sure that I have to rewrite most of the code, but these patches work. 

Fourth patch is to find the minimal delta among p1, p2, rev-1. But it is no where near to implementation. It drags down the performance by 10x times.  

Siggestions are welcome.

[0] http://mercurial.selenic.com/wiki/in3xes (See work progress section at the bottom)