Found #36848 whose last comment seems to refer to this but that was originally about something else and now closed.
Steps to reproduce:
- Goto http://en.m.wikipedia.org/wiki/Google_Authenticator
- Expand one of the sections, e.g. "Open Source status on Android"
- Click a wiki link within the section, e.g. "Red Hat"
- Wait for the new page to load
- Press the browser back button
Page to be rendered as previously with the "Open Source status" section expanded and last position in the document shown
Page is display with all sections collapsed.