Steps to Reproduce:
# Go to Internet Explorer 11 at Windows 7 or 8 (or 10 when using the IE mode in MS Edge).
# When logged-in, go to your [[https://en.wikipedia.org/wiki/Special:Preferences|Preferences settings page]], or click "[[https://en.wikipedia.org/wiki/Special:Preferences#mw-prefsection-betafeatures|Beta]]".
# If "Preferences" is clicked, then click "Beta features" tab
# Enable "New wikitext mode".
# If "Temporarily disable the visual editor while it is in beta" option is checkmarked, then de-checkmark the option to re-enable the selection menu.
# Under the selection menu, select "Always give me the source editor".
# When settings are saved, go to any page, like a sandbox or an article.
# Click the "Edit" tab.
Actual Results:
- The URL address bar says [[https://en.wikipedia.org/wiki/undefined?action=edit|`https://en.wikipedia.org/wiki/undefined?action=edit`]]
- When at any subpage of a page and using steps to reproduce, the URL address bar says `https://en.wikipedia.org/wiki/<article/page>/undefined?action=edit`, e.g. https://en.wikipedia.org/wiki/Wikipedia:WikiProject_Cricket/undefined?action=edit
- When "Article" tab is clicked to exit the NWE, the address bar still retains the above URL.
- When a page is refreshed/reloaded (i.e. press {key F5}), the browser directs a user to (literally) the disambiguation page about "Undefined".
Expected Results:
- In Chrome and Firefox, the URL address bar still remains as `https://en.wikipedia.org/wiki/<article/page>?action=edit`.
- When either exiting the NWE or refreshing a page, the browser should not redirect a user to that disambiguation page.
- A user at IE11 should not have experienced the "Actual Results" described above.