Add test for missing commits when range-copying after a paste

After a successful paste, the "X commits copied" indicator hides and
DidPaste is set, but the buffer is not cleared. If the user then
range-selects multiple commits and presses shift+C, every Add() call
rebuilds the set via SelectedHashSet(), which returns empty while
DidPaste is true; each iteration of the copy loop therefore overwrites
the previous one and only the last commit in the range survives.

pkg/integration/tests/test_list.go

@@ -97,6 +97,7 @@ var tests = []*components.IntegrationTest{
 	cherry_pick.CherryPickDuringRebase,
 	cherry_pick.CherryPickMerge,
 	cherry_pick.CherryPickRange,
+	cherry_pick.CherryPickRangeAfterPaste,
 	commit.AddCoAuthor,
 	commit.AddCoAuthorRange,
 	commit.AddCoAuthorWhileCommitting,