Add a features list to branches.cache to detect caches of old hg versions.
The leading space in the written file makes sure that the feature list never
can match an existing version, even if the first feature can be read as hex.
Additionally old hg versions display the id with --debug, too.
#!/bin/sh
hg init rep
cd rep
mkdir dir
touch foo dir/bar
hg -v addremove
hg -v commit -m "add 1" -d "1000000 0"
cd dir/
touch ../foo_2 bar_2
hg -v addremove
hg -v commit -m "add 2" -d "1000000 0"
cd ..
hg init sim
cd sim
echo a > a
echo a >> a
echo a >> a
echo c > c
hg commit -Ama
mv a b
rm c
echo d > d
hg addremove -s 0.5
hg commit -mb