On the prefs-tab, when I input tags to be ignored, they appear on the page instantly and look fine, but the POST to actually save them to the server concatenates them sometimes.
I can reproduce the bug in Firefox and Google on Win XP, both when I type a tag in by hand and when I click on one of the autocomplete-suggestions.
Two screenshots of the problem, captured in firebug:
here the last two tags,
c are combined to
And this concatenated tag really get's stored and displayed when I load the page the next time