Textinput: last word inputted was duplicated after press "Password" button

Reproduce Steps:
1. launch qmlviewer and load textinput.qml;
2. press green textinput field;
3. input "Hello ", then input "World"
4. before the line under "World" disappearing, press the button with a green hook on the left bottom of the screen;
5. press "Password" button
6. press "Normal" button

Expected Result:
After Step 5, 11 asterisks should be displayed in the green textinput field. After Step 6, "Hello World" should be displayed in the green textinput field.

Actual Result:
After Step 5, 16 asterisks are displayed. After Step 6, "Hello WorldWorld" is displayed, the last world is duplicated.