For your future searching pleasure ... these were pretty easy to find.
I went to bugzilla andvanced search: https://bugs.eclipse.org/bugs/query.cgi
Selected 'Eclipse' classification, put "eontent type" in Summary query
line (with "contains all the strings"). Searched, found about a 100
bungs. Then used my browser search to look for 'extension' in that list,
and found a few.