MathOverflow will be down for maintenance for approximately 3 hours, starting Monday evening (06/24/2013) at approximately 9:00 PM Eastern time (UTC-4).
show/hide this revision's text 1 [made Community Wiki]

This question reminded me of the following article of A. Neeman with an appendix by P. Deligne:

A counterexample to a 1961 “theorem” in homological algebra