Bug 1720591: Remove unused patch_main() for Python < 3.4 on Windows r=ahal

Now that we use Python 3.6+, this code is obsolete.

Differential Revision: https://phabricator.services.mozilla.com/D119929

build/mach_bootstrap.py

@@ -247,10 +247,6 @@ def bootstrap(topsrcdir):
         # The resource module is UNIX only.
         pass
 
-    from mozbuild.util import patch_main
-
-    patch_main()
-
     def resolve_repository():
         import mozversioncontrol
 

python/mozbuild/mozbuild/util.py

@@ -1402,71 +1402,6 @@ def write_indented_repr(f, o, indent=4):
     f.write(result)
 
 
-def patch_main():
-    """This is a hack to work around the fact that Windows multiprocessing needs
-    to import the original main module, and assumes that it corresponds to a file
-    ending in .py.
-
-    We do this by a sort of two-level function interposing. The first
-    level interposes forking.get_command_line() with our version defined
-    in my_get_command_line(). Our version of get_command_line will
-    replace the command string with the contents of the fork_interpose()
-    function to be used in the subprocess.
-
-    The subprocess then gets an interposed imp.find_module(), which we
-    hack up to find the main module name multiprocessing will assume, since we
-    know what this will be based on the main module in the parent. If we're not
-    looking for our main module, then the original find_module will suffice.
-
-    See also: http://bugs.python.org/issue19946
-    And: https://bugzilla.mozilla.org/show_bug.cgi?id=914563
-    """
-    # XXX In Python 3.4 the multiprocessing module was re-written and the below
-    # code is no longer valid. The Python issue19946 also claims to be fixed in
-    # this version. It's not clear whether this hack is still needed in 3.4+ or
-    # not, but at least some basic mach commands appear to work without it. So
-    # skip it in 3.4+ until we determine it's still needed.
-    if sys.platform == "win32" and sys.version_info < (3, 4):
-        import os
-        from multiprocessing import forking
-
-        global orig_command_line
-
-        # Figure out what multiprocessing will assume our main module
-        # is called (see python/Lib/multiprocessing/forking.py).
-        main_path = getattr(sys.modules["__main__"], "__file__", None)
-        if main_path is None:
-            # If someone deleted or modified __main__, there's nothing left for
-            # us to do.
-            return
-        main_file_name = os.path.basename(main_path)
-        main_module_name, ext = os.path.splitext(main_file_name)
-        if ext == ".py":
-            # If main is a .py file, everything ought to work as expected.
-            return
-
-        def my_get_command_line():
-            with open(
-                os.path.join(os.path.dirname(__file__), "fork_interpose.py"), "rU"
-            ) as fork_file:
-                fork_code = fork_file.read()
-            # Add our relevant globals.
-            fork_string = (
-                "main_file_name = '%s'\n" % main_file_name
-                + "main_module_name = '%s'\n" % main_module_name
-                + fork_code
-            )
-            cmdline = orig_command_line()
-            # We don't catch errors if "-c" is not found because it's not clear
-            # what we should do if the original command line is not of the form
-            # "python ... -c 'script'".
-            cmdline[cmdline.index("-c") + 1] = fork_string
-            return cmdline
-
-        orig_command_line = forking.get_command_line
-        forking.get_command_line = my_get_command_line
-
-
 def ensure_bytes(value, encoding="utf-8"):
     if isinstance(value, six.text_type):
         return value.encode(encoding)