evolve: run in a single transaction
This speeds up `hg evolve --all` of a stack of 24 commits in the hg
repo from 11.5s to 3.7s (3x). As can be seen in the tests, it also
avoid some warnings about transiently unstable commits.
$ cat >> $HGRCPATH <<EOF
> [ui]
> logtemplate={rev}:{node|short}[{bookmarks}] ({obsolete}/{phase}) {desc|firstline}\n
> [extensions]
> EOF
$ echo "evolve=$(echo $(dirname $TESTDIR))/hgext3rd/evolve/" >> $HGRCPATH
$ mkcommit() {
> echo "$1" > "$1"
> hg add "$1"
> hg ci -m "add $1"
> }
$ hg init repo
$ cd repo
$ mkcommit a
$ mkcommit b
test disabling commands
$ cat >> .hg/hgrc <<EOF
> [experimental]
> evolution=createmarkers
> allowunstable
> exchange
> EOF
$ hg prune
hg: unknown command 'prune'
(use 'hg help' for a list of commands)
[255]