It might be a good idea to put a note in the upgrade instructions at
regarding the UTF setting.
The automatic upgrade function doesn't work for me on one of my blogs so I manually upgraded. The instructions say, "Compare your existing file with the new installation file which is named wp-config-sample.php. Either transfer your settings to the sample-file and rename it to wp-config.php or copy the new statements from the sample file into your current file."
I copied the new statements, including
into my config file and ended up with weird characters in my blog posts in place of quotation marks and some other punctuation. Although I'm not 100% sure, I think I fixed it by going back and removing those lines from the config file.