Improve detection of function name in doctest parsing #14327
Description
When testing sage.rings.padics.factory, a failure in Qq is shown in the doctest report as sage.rings.padics.factory.? because of the indentation of the following lines.
This is due to a problem in the indentation tracking in sage.doctest.sources.
Depends on #12415
Component: doctest framework
Issue created by migration from https://trac.sagemath.org/ticket/14327