RunnerMatchesModel is backed by a list. When this list changes
RunnerManagerModel add/removes the new number of rows then called
dataChanged on everything that remained.
It's a common pattern, but not a great one. Especially with QtQuick
where moving a delegate is faster than updating all the properties of an
existing one - unfortunately I can't find a nice solution to do this
properly in linear time.
The problem with the current code is we update the entire list in the
insert/remove rows. This is a violation of the model rules as we're
updating rows outside the rows listed inside begin/remove rows.
It works, but Qt's model test fails.
We also have a lot of duplicates of a crash in QtQuick after runner
model changes, bug 369430. I think it could be related, but can't
This patch updates the rows that exist in both the before and after
models before adding/removing the remaining rows.