type git, type hg, this script don't care

git_or_hg.sh

export ORIGINAL_GIT=`which git`
export ORIGINAL_HG=`which hg`

git() {
  if [ -d .hg ]; then
    echo "perhaps you meant hg?"
    "$ORIGINAL_HG" $@
  else
    "$ORIGINAL_GIT" $@
  fi
}

hg() {
  if [ -d .git ]; then
    echo "perhaps you meant git?"
    "$ORIGINAL_GIT" $@
  else
    "$ORIGINAL_HG" $@
  fi
}