In cases, when key already exist, but commented out without space
(ie "#key) and is not in default section, it's not updated with
sectdict.insert statement. That is possible happens because
self._sections keys are protected and can't be overwritten (at least
new assignment makes no difference)
Change-Id: Ie0c588a2d559bd38c68b3d018e547a036d83214c
Closes-Bug: #1889547