tests: demonstrate the interrupted evolve does not set p2
This patch adds a test to demonstrate issue5927 which is about evolving not
setting p2 correctly in interruption.
#!/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