evolve: don't use graftstate for continuing `hg evolve` Before this patch, if user runs `hg evolve`, we read the evolve state, write a graftstate from that information and run graft command. This patch replaces that logic with new logic which does not depends on the graft state. The new logic is very filtered part of logic from graft command. We did not require a lot of opts checking and filtering revs logic from the graft command as our use case is fixed. This is the start of series/work which will make `hg evolve` better and have a good statefile for itself.

#require test-repo

  $ checkflake8() {
  >   if ! (which flake8 > /dev/null); then
  >     echo skipped: missing tool: flake8;
  >     exit 80;
  >   fi;
  > };
  $ checkflake8

Copied from Mercurial core (60ee2593a270)

  $ cd "`dirname "$TESTDIR"`"

run flake8 if it exists; if it doesn't, then just skip

  $ hg files -0 'set:(**.py or grep("^#!.*python")) - removed()' 2>/dev/null \
  > | xargs -0 flake8