Fix upgrade_oh_my_zsh function deprecation

lib/cli.zsh

@@ -201,10 +201,14 @@ function _omz::pr::test {
 }
 
 function _omz::update {
+    # Run update script
     env ZSH="$ZSH" sh "$ZSH/tools/upgrade.sh"
     # Update last updated file
     zmodload zsh/datetime
     echo "LAST_EPOCH=$(( EPOCHSECONDS / 60 / 60 / 24 ))" >! "${ZSH_CACHE_DIR}/.zsh-update"
     # Remove update lock if it exists
     command rm -rf "$ZSH/log/update.lock"
+    # Restart the zsh session
+    _omz::log info "restarting the zsh session..."
+    [[ -z "$SHELL" ]] && exec ${SHELL#-} || exec zsh
 }

lib/functions.zsh

@@ -7,8 +7,20 @@ function uninstall_oh_my_zsh() {
 }
 
 function upgrade_oh_my_zsh() {
-  echo >&2 "${fg[yellow]}Note: \`$0\` is deprecated. Use \`omz update\` instead.$reset_color"
-  omz update
+  if (( $+functions[_omz::update] )); then
+    echo >&2 "${fg[yellow]}Note: \`$0\` is deprecated. Use \`omz update\` instead.$reset_color"
+  fi
+
+  # Run update script
+  env ZSH="$ZSH" sh "$ZSH/tools/upgrade.sh"
+  # Update last updated file
+  zmodload zsh/datetime
+  echo "LAST_EPOCH=$(( EPOCHSECONDS / 60 / 60 / 24 ))" >! "${ZSH_CACHE_DIR}/.zsh-update"
+  # Remove update lock if it exists
+  command rm -rf "$ZSH/log/update.lock"
+  # Restart the zsh session
+  _omz::log info "restarting the zsh session..."
+  [[ -z "$SHELL" ]] && exec ${SHELL#-} || exec zsh
 }
 
 function take() {