Don't confirm fork for owned sandboxes

Author: CompuIves

packages/app/src/app/overmind/namespaces/editor/actions.ts

@@ -306,6 +306,7 @@ export const forkSandboxClicked: AsyncAction = async ({
 }) => {
   if (
     state.editor.currentSandbox.owned &&
+    !state.editor.currentSandbox.customTemplate &&
     !effects.browser.confirm('Do you want to fork your own sandbox?')
   ) {
     return;