add deprecation warning for push/pop commands

plugins/pyenv-version-ext-compat/bin/pyenv-sh-pop

@@ -5,6 +5,8 @@ set -e
 
 IFS=: versions=($(pyenv-version-name))
 
+echo "WARNING: The \`pop' command will be removed from pyenv. Please install https://github.com/yyuu/pyenv-version-ext." 1>&2
+
 length="${#versions[@]}"
 PYENV_VERSION_NAMES=()
 for ((i=0; i<length-1; i++)); do

plugins/pyenv-version-ext-compat/bin/pyenv-sh-push

@@ -7,6 +7,8 @@ IFS=: PYENV_VERSION_NAMES=($(pyenv-version-name))
 versions=("$@")
 PYENV_VERSION_NAMES=("${PYENV_VERSION_NAMES[@]}" "${versions[@]}")
 
+echo "WARNING: The \`push' command will be removed from pyenv. Please install https://github.com/yyuu/pyenv-version-ext." 1>&2
+
 if [ -n "$PYENV_VERSION" ]; then
   IFS=: PYENV_VERSION="${PYENV_VERSION_NAMES[*]}"
   echo "export PYENV_VERSION=\"${PYENV_VERSION}\""