History must be cleared twice to be fully cleared

Submitted by Jean-Philippe Fleury

Assigned to Mike Massonnet

Say the clipboard is empty.

Copy with "Ctrl+C" some text from any software (for example gedit). There's now 1 item in the clipboard history.
Click on the clipman icon on the panel and choose "Clear".

Result: the item is not cleared, so there's still 1 item in the history.

Result: the history is now cleared. No item remains.

Say the clipboard is empty.

Copy with "Ctrl+C" some text from any software (for example gedit). There's now 1 item in the clipboard history.
Copy again with "Ctrl+C" some text. There's now 2 items in the history.
Copy again with "Ctrl+C" some text. There's now 3 items in the history.
Click on the clipman icon on the panel and choose "Clear".

Result: the first two items are cleared, but the last one remains, so there's still 1 item in the history.

Result: the history is now cleared. No item remains.

xfce4-clipman-plugin 1.2.6
In the preferences, I checked "Store last copied image", "Ignore selections" and "Reorder history items". All other checkboxes are unchecked. I also have "Size of the history: 10" and "Paste instantly: None".
Xubuntu 14.10 Beta 1 (64-bit)
Note that I didn't have this bug with xfce4-clipman-plugin 1.2.5 on Xubuntu 14.04.