tests/testlib/common.sh

black: format the codebase with 23.3.0

The CI has moved to 23.3.0, which is the last version that supports 3.7
at runtime, so we should honor this change.

# skip-blame mass-reformating only

mkcommit() {
   name="$1"
   shift
   echo "$name" > "$name"
   hg add "$name"
   hg ci -m "$name" "$@"
}