This goes with bug report https://bugs.kde.org/show_bug.cgi?id=388798
The unit test of kLineEdit was previously checking incorrectly that textEmitted _HAD_ been emitted when the text is changed with setText(). This is undesired behaviour.
This patch fixes the unit test, and changes the problematic behaviour.
In addition, the private signal is renamed from _k_textChanged to _k_textEmitted to better reflect the desired semantics inline with QLineEdit.
In addition this is the underlying cause of bug https://bugs.kde.org/show_bug.cgi?id=373004 in kdevelop (and probably several others).