Bug 1869690 - Hack the vendored pip's vendored pkg_resources to support python 3.12. r=ahochheiden,mach-reviewers

While bug 1857470 is set to fix the problem with a pip upgrade, it is
going to take some time. In the meanwhile, we can just do the minimal
thing that makes things work well enough for a build to go through.

Differential Revision: https://phabricator.services.mozilla.com/D196256

third_party/python/pip/pip/_vendor/pkg_resources/__init__.py

@@ -2161,7 +2161,8 @@ def resolve_egg_link(path):
     return next(dist_groups, ())
 
 
-register_finder(pkgutil.ImpImporter, find_on_path)
+if hasattr(pkgutil, 'ImpImporter'):
+    register_finder(pkgutil.ImpImporter, find_on_path)
 
 if hasattr(importlib_machinery, 'FileFinder'):
     register_finder(importlib_machinery.FileFinder, find_on_path)
@@ -2312,7 +2313,8 @@ def file_ns_handler(importer, path_item, packageName, module):
         return subpath
 
 
-register_namespace_handler(pkgutil.ImpImporter, file_ns_handler)
+if hasattr(pkgutil, 'ImpImporter'):
+    register_namespace_handler(pkgutil.ImpImporter, file_ns_handler)
 register_namespace_handler(zipimport.zipimporter, file_ns_handler)
 
 if hasattr(importlib_machinery, 'FileFinder'):