Bug 1775183 - Remove fork_interpose.py. r=firefox-build-system-reviewers,nalexander

Its use was removed in bug 1720591.

Differential Revision: https://phabricator.services.mozilla.com/D149840

.flake8

@@ -17,7 +17,6 @@ exclude =
     netwerk/protocol/http/make_incoming_tables.py,
     python/devtools/migrate-l10n/migrate/main.py,
     python/l10n/fluent_migrations,
-    python/mozbuild/mozbuild/fork_interpose.py,
     security/manager/ssl/tests/unit,
     servo/components/style,
     testing/condprofile/condprof/android.py,

python/mozbuild/mozbuild/fork_interpose.py

@@ -1,42 +0,0 @@
-# This Source Code Form is subject to the terms of the Mozilla Public
-# License, v. 2.0. If a copy of the MPL was not distributed with this file,
-# You can obtain one at http://mozilla.org/MPL/2.0/.
-
-# This source code is indirectly used in python/mozbuild/mozbuild/util.py and
-# is not meant to be imported. This file can be entirely deleted when the
-# transition to Python 3 is complete.
-
-import imp
-import os
-import sys
-
-orig_find_module = imp.find_module
-
-def my_find_module(name, dirs):
-    if name == main_module_name:
-        path = os.path.join(dirs[0], main_file_name)
-        f = open(path)
-        return (f, path, ('', 'r', imp.PY_SOURCE))
-    return orig_find_module(name, dirs)
-
-# Don't allow writing bytecode file for the main module.
-orig_load_module = imp.load_module
-
-def my_load_module(name, file, path, description):
-    # multiprocess.forking invokes imp.load_module manually and
-    # hard-codes the name __parents_main__ as the module name.
-    if name == '__parents_main__':
-        old_bytecode = sys.dont_write_bytecode
-        sys.dont_write_bytecode = True
-        try:
-            return orig_load_module(name, file, path, description)
-        finally:
-            sys.dont_write_bytecode = old_bytecode
-
-    return orig_load_module(name, file, path, description)
-
-imp.find_module = my_find_module
-imp.load_module = my_load_module
-from multiprocessing.forking import main
-
-main()

tools/lint/black.yml

@@ -4,7 +4,6 @@ black:
     exclude:
         - gfx/harfbuzz/src/meson.build
         - layout/style/ServoCSSPropList.mako.py
-        - python/mozbuild/mozbuild/fork_interpose.py
         - python/mozbuild/mozbuild/test/frontend/data/reader-error-syntax/moz.build
         - testing/mozharness/configs/test/test_malformed.py
         - testing/web-platform/tests