blender-2.80.0-git.53c63db-windows64 (and earlier, but not in 2.79)

Steps:

1. Copy script
2. Paste it to python console
3. Invoke Delete operator MANUALLY via X key and Check Delete globally (this is important, click it by mouse)

4. Paste script again.

After that:
A) Sometimes C.collection.objects.items() may crash.

B) C.collection.objects[] become invisible. It is in a *Master collection*, BUT not selectable: C.collection.objects['o'].select_set('SELECT') failing.

o = D.objects.new('o', D.armatures.new('a'))
C.collection.objects.link(o)
bpy.ops.object.select_all(action='SELECT')
C.collection.objects['o'].select_set('SELECT')