gh-113329: Catch OSError in doctest finder

Fixes #113329, which occurs when running doctests in a class docstring in a REPL environment. Since Python 3.10, an OSError is raised when the class source code cannot be found.

Author: stenwessel

Doc/library/inspect.rst

@@ -560,6 +560,7 @@ Retrieving source code
 .. function:: getfile(object)
 
    Return the name of the (text or binary) file in which an object was defined.
+   An :exc:`OSError` is raised if the source code cannot be retrieved.
    This will fail with a :exc:`TypeError` if the object is a built-in module,
    class, or function.
 
@@ -573,9 +574,10 @@ Retrieving source code
 .. function:: getsourcefile(object)
 
    Return the name of the Python source file in which an object was defined
-   or ``None`` if no way can be identified to get the source.  This
-   will fail with a :exc:`TypeError` if the object is a built-in module, class, or
-   function.
+   or ``None`` if no way can be identified to get the source.  An :exc:`OSError` is
+   raised if the source code cannot be retrieved.
+   This will fail with a :exc:`TypeError` if the object is a built-in module,
+   class, or function.
 
 
 .. function:: getsourcelines(object)

Lib/doctest.py

@@ -923,7 +923,7 @@ def find(self, obj, name=None, module=None, globs=None, extraglobs=None):
         # given object's docstring.
         try:
             file = inspect.getsourcefile(obj)
-        except TypeError:
+        except (TypeError, OSError):
             source_lines = None
         else:
             if not file: