ipython/ipython — pull request #4253 by Carreau (2013-09-22 15:37:15+00:00)
Title: fixes #4039.

Issues is that $(selector).val() return the associated text if no data
is present (hence one cannot associate explicitely an option to
"undefined")

fix in doc and example.

Ping @damianavila that might be affected by this slight change, but shouldn't has we were obviously already storing '-' in metadata.