message: build/pre-release: rename merge function
diff: main() {
  ensure_clean_index
  - merge_unstable_to_matser
  + merge_to_unstable
  run_preversion_tests
  bump_version
  run_build
  @@ -21,7 +21,7 @@ ensure_clean_index() {
  fi
  }
  -merge_unstable_to_matser() {
  +merge_to_unstable() {
  echo_funcname
  INITIAL_BRANCH=$(git rev-parse --abbrev-ref HEAD)
  