evolve: fixed lock acquire before checking state Before checking the states `repo.lock()` and `repo.wlock()` need to be acquired. This was not happening in `evolve()` earlier. This patch creates a seperate `_performevolve()` funtion which can be then called with locks acquired. This also removes the redundant lock acuquiring of `abortevolve` and `continueevolve` as lock is now taken earlier.

#!/bin/bash
set -euox pipefail

unset GREP_OPTIONS
NOTOPIC="--config experimental.topic-mode=ignore"

compatbranches=`hg branches --quiet | grep 'mercurial-' | grep -v ':' | sort -n --reverse`
prev='stable'
for branch in $compatbranches; do
    hg up $branch
    hg merge $prev
    hg commit -m "test-compat: merge $prev into $branch"
    prev=$branch
done