From google webmaster tools for enwiki...

To: webmaster of http://en.wikipedia.org/
Google systems have detected issues with your app's pages. In some cases, a click on the "Back" button does not return the user to the search results page. Out of 77 URIs we've tested in the past 7 days, 66 URIs had this issue. This can make users feel trapped or confused because they can’t navigate properly. Therefore, we may consider not showing deep links to those app pages in our mobile search results in the future.
Here’s how you can fix this:
1 Start with the example URIs
Use the list of sample of URIs below that show where we detected this behavior. Common causes for this error are overwriting the default back button behaviour, redirecting to another activity when launching an deeplink, or having pop-up dialogs (e.g. sign-in, or confirmation of leaving the app).
2
Use the testing tool
Our deep links testing tool can help you more easily test your app’s behavior to ensure the back button behaves correctly.
Try it now
3 Verify the fix
Test the deep links with your attached device or emulator: exit the app, open the deep link, and press the back button. Confirm that the device displays the previous context and not your app.
The following example URIs had back-button issues:

android-app://org.wikipedia/http/en.m.wikipedia.org/wiki/Government_of_Zanzibar_v_British_Aerospace_(Lancaster_House)_Ltd

android-app://org.wikipedia/http/en.m.wikipedia.org/wiki/2013_United_Football_League_(Philippines)

android-app://org.wikipedia/http/en.m.wikipedia.org/wiki/Station_(frontier_defensive_structure)

android-app://org.wikipedia/http/en.m.wikipedia.org/wiki/Fruela_D%C3%ADaz

android-app://org.wikipedia/http/en.m.wikipedia.org/wiki/Far_Reaching_Ministries