Name of placeholder in layout gets reset to placeholder basename when adding slide
The clone_placeholder method on _BaseShapes makes a call to _next_ph_name to get the name of the new shape. If the placeholder name in the layout has been changed from the default this causes the placeholder in the new slide to be set to the default name instead of inheriting the name from the layout placeholder because _next_ph_name does a lookup on the ph_type argument to get the default basename.
If _next_ph_name can be changed from:
def _next_ph_name(self, ph_type, id, orient):
to
def _next_ph_name(self, name, id, orient):
It would allow the name to be inherited.
This is important because uniquely identifying the placeholders in the layout makes it much easier to programmatically assign values to the placeholder in the new slide because the name has context (e.g. custom layout name: "project_name" vs. derived basename: "Text Placeholder 1")