Steps to reproduce: 1. When the page has finished loading notice that you can scroll the menu on the left and the content on the right. 2. Now search, using Cmd+f, for "saved to the server". 3. Try again to scroll the fixed menu on the left. 4. Pressing Esc to cancel further searching fixes the scroll once again. In step 2 it seems to me that the string being searched for needs to be enough down the page in order to trigger an automatic scroll to that part. So it may depend on the size of your screen.
Currently running r156764 but I've noticed this for a couple of weeks (at least) now.
Doesn't work for me in Safari 6.0.5 either.
Created attachment 213261 [details] Simplified test case exhibiting similar behaviour. Triggered this time using the string "Morbi sit".