At sup 0.15 start: invalid byte sequence in UTF-8

```
--- ArgumentError from thread: load threads for thread-index-mode
invalid byte sequence in UTF-8
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/person.rb:10:in `gsub'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/person.rb:10:in `initialize'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/person.rb:82:in `new'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/person.rb:82:in `from_name_and_email'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:247:in `block in build_message'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:248:in `[]'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:248:in `build_message'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:161:in `block (2 levels) in each_id_by_date'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/thread.rb:338:in `call'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/thread.rb:338:in `block in load_n_threads'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:161:in `block in each_id_by_date'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:284:in `block in each_id'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:284:in `each'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:284:in `each_id'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/index.rb:161:in `each_id_by_date'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/thread.rb:334:in `load_n_threads'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/modes/thread_index_mode.rb:674:in `load_n_threads'
(eval):12:in `load_n_threads'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup/modes/thread_index_mode.rb:658:in `block in load_n_threads_background'
/var/lib/gems/1.9.1/gems/sup-0.15.0/lib/sup.rb:87:in `block in reporting_thread'
```