psi confuse gajim when changing topic
It seems that psi send a element with <subject>foo</subject><body>/me has changed the topic to : foo</body>, that confuse gajim. This is likely be a rest of groupchat 1.0, but there is no specification to check this.
According to xep 0045, "The subject is changed by sending a message of type "groupchat" to the <room@service>, containing no body but a <subject/> that specifies the new subject:" ( point 8.1 of the spec ).
So, gajim should ignore such part of the message ( and psi should be fixed to be compatible with muc, that is a different story, see bug ), here is a patch against svn that remove this part of the code.