Steps to reproduce:
1. Create webcontent and publish in control panel
2. Click webcontent that you just created to edit
3. Modify Content
4. After you modify webcontent, change language to something other that english
5. You will get a popup asking "would you like to save the changes made to this language?" and click ok
6. Modify content again
7. Click publish
Got error: "Another user has made changes since you started editing. Please copy your changes and try again."
It is happens because on step 5 new version of article are stored (1.1) - but after storing it is redirected back to edit original version (1.0) but with new language.
So, on step 7 we trying to update original version 1.0 - which is older then version already stored in DB (1.1) - and this is produced a bug.
List used for redirect after switching language created in docroot/html/portlet/journal/edit_article.jsp in JS function getLanguageViewURL - if to remove version param from it - working almost as expected.