Custom Widgets lost when theme is re-activated while the widget plugin is inactive

[asadkn]

It could be a rare issue for others, but it's a regular process for my use-case.

Custom Widgets are no longer shown in the widget area when theme is de-activated and re-activated while the plugin that provided one of the widgets is inactive.

Steps: (Assumes, twenty fourteen is active)

1. Install Slim Jetpack plugin (or any other plugin that provides a widget). I enabled the Extra Sidebar Widgets from Settings > Slim Jetpack.

2. Add one of the Slim Jetpack widgets to the "Primary Sidebar" for example "Gravatar Profile (Jetpack)".

3. De-active Slim Jetpack.

4. Activate "Twenty Thirteen" theme.

5. Activate "Twenty Fourteen" theme.

6. Activate "Slim Jetpack". Unfortunately, the custom widget is lost.

If you had normally de-activated and re-activated Slim Jetpacks, the Primary Sidebar would be fine. If you had done 4 and 5 without 3, everything would be good.

But doing the steps as above, the widget is no longer in the sidebar - not even under Inactive Widgets.