When adding a second version of a document to documents and media, the back button sometimes does not display, leaving the user unable to return directly to the previous page.
Steps to reproduce:
1. start liferay portal
2. add documents & media portal
3. create a .txt file to use named aaa.txt
4. add > basic document > aaa.txt
5. click on aaa.txt > edit > browse > aaa.txt
after saving the file, the subsequent screen will lack a 'Back' link