evolve: move code to track progress and start node This makes it easier to refactor the evolve function in this serie of patches.

evolve: renaming of a variable tro was not a really descriptive name, replacing it with nexttrouble.

evolve: refactoring of the code displaying error when no trouble found Before this patch, we had many return statements in the evolve function especially in the part in charge of displaying errors when no troubles were found. We move this code in a separate function.

evolve: refactor code computing stats of obsolescence markers Duplicated code removal by extracting a function.

evolve: refactoring of code related to pushing obs markers This removes duplicated code for the pushobsmarkers logic

merge with stable bunch of cleanup on stable

update readme

evolve: update cmddebugrecordpruneparents to the new markers creation API The parents information are now first class citizen. (caught by laurent using pylint)

evolve: drop useless return This return statement is never reached. This a actually a good new because its variable was undefined. We remove it. (caught by laurent using pylint)

evolve: add missing import (caught by pylint)

evolve: improve transaction related code to use the lock module Refactored some of the places where we are using locking in evolve to use the lock module and write less code. This should also fix a couple of bug where tr could be None at release time.

evolve: remove unused variables As suggested by pyflakes, remove 5 unused variables in the evolve module.

evolve: remove unused code in _evolveany remove some code that was doing nothing useful in _evolveany.

evove: remove unused imports Three imports where unused in the evolve module.