Yes. Very related. Problem solved. So it's an Eclipse bug.
To resolve either remove P2 as in the Stackoverflow link or even easier :
1. Export sites to bookmarks.xml
2. Edit this file and append a forward slash at the end of every URL where it is missing.
3. Delete all sites
4. Re-import edited bookmarks.xml
5. Sigh with relief as it works.
yes - P2 has a tendency to be tricky as soon as you start using it ;)