no compatible signature for decorated function in projector test

Trunk on superfly machine

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ERROR: test_source_select_edit_button (tests.interfaces.openlp_core_ui.test_projectorsourceform.ProjectorSourceFormTest)
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Traceback (most recent call last):
  File "/usr/lib/python3.5/unittest/mock.py", line 1157, in patched
    return func(*args, **keywargs)
  File "/home/raoul/Projects/OpenLP/OpenLP/permission-error/tests/interfaces/openlp_core_ui/test_projectorsourceform.py", line 132, in test_source_select_edit_button
    select_form.exec(projector=self.projector)
  File "/home/raoul/Projects/OpenLP/OpenLP/permission-error/openlp/core/ui/projector/sourceselectform.py", line 448, in exec
    self.button_box.clicked.connect(self.button_clicked)
TypeError: decorated slot has no signature compatible with clicked(QAbstractButton*)

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ERROR: test_source_select_noedit_button (tests.interfaces.openlp_core_ui.test_projectorsourceform.ProjectorSourceFormTest)
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Traceback (most recent call last):
  File "/usr/lib/python3.5/unittest/mock.py", line 1157, in patched
    return func(*args, **keywargs)
  File "/home/raoul/Projects/OpenLP/OpenLP/permission-error/tests/interfaces/openlp_core_ui/test_projectorsourceform.py", line 152, in test_source_select_noedit_button
    select_form.exec(projector=self.projector)
  File "/home/raoul/Projects/OpenLP/OpenLP/permission-error/openlp/core/ui/projector/sourceselectform.py", line 448, in exec
    self.button_box.clicked.connect(self.button_clicked)
TypeError: decorated slot has no signature compatible with clicked(QAbstractButton*)