Source list doesn't update right away when you delete multiple sources

[sssoleileraaa]

STR

1. run make dev
2. run the client and log in
3. delete both sources right away within one sync period

Expected

Next sync both source widgets in the source list are gone

Actual

Next sync the first source widget disappears. Next sync after that the second source widget disappears.

You also see the "Nothing to see just yet" and "Deleting..." message at the same time.

Why is this happening?

In the source list update method we delete items in the QListWidget that we are iterating through which changes the number of iterations we make in the deletion loop:

securedrop-client/securedrop_client/gui/widgets.py

Lines 795 to 810 in aa89e70

	for i in range(self.count()):
	list_item = self.item(i)
	list_widget = self.itemWidget(list_item)
	if list_widget and list_widget.source_uuid not in source_uuids:
	if list_item.isSelected():
	self.setCurrentItem(None)
	try:
	del self.source_widgets[list_widget.source_uuid]
	except KeyError:
	pass
	self.takeItem(i)
	deleted_uuids.append(list_widget.source_uuid)
	list_widget.deleteLater()

[sssoleileraaa]

Another STR that shows the problem with the current source-deletion logic from the server-side deletion perspective:

STR 2

1. run make dev
2. run the client and log in
3. NUM_SOURCES=0 make dev

Expected

Next time the client can connect to the server during a sync, both source widgets in the source list are gone

Actual

Next sync the first source widget disappears. Next sync after that the second source widget disappears.