'Respond to changes to the `summary` field
Newlines can enter the `summary` field when pasting, which is
undesirable.  Break the pasted value apart into the separate
(summary, description) values and move the description over to the
"extended description" field.'

def commit_summary_changed(self, value):

    if (u'\n' in value):
        (summary, description) = value.split(u'\n', 1)
        description = description.lstrip(u'\n')
        cur_description = self.description.value()
        if cur_description:
            description = ((description + u'\n') + cur_description)
        self.summary.set_value(summary, block=True)
        self.description.set_value(description)
    self._commit_message_changed()
