Bug 1739486 - Hack around pypa/virtualenv#2208. r=mhentges

The virutalenv hack is in the fedora-distributed version of
virtualenv... Presumably eventually will become unnecessary once they
provide a proper "venv" distutils?

This patch applies both before and after the bump in comment 5, so your
call.

Differential Revision: https://phabricator.services.mozilla.com/D130410

python/mach/mach/virtualenv.py

@@ -416,13 +416,20 @@ def _site_packages_dir(self):
         # because it's needed by the "virtualenv" package.
         from distutils import dist
 
+        normalized_venv_root = os.path.normpath(self.virtualenv_root)
+
         distribution = dist.Distribution({"script_args": "--no-user-cfg"})
         installer = distribution.get_command_obj("install")
-        installer.prefix = os.path.normpath(self.virtualenv_root)
+        installer.prefix = normalized_venv_root
         installer.finalize_options()
 
         # Path to virtualenv's "site-packages" directory
-        return installer.install_purelib
+        path = installer.install_purelib
+        local_folder = os.path.join(normalized_venv_root, "local")
+        # Hack around https://github.com/pypa/virtualenv/issues/2208
+        if path.startswith(local_folder):
+            path = os.path.join(normalized_venv_root, path[len(local_folder) + 1 :])
+        return path
 
 
 def get_archflags():

third_party/python/virtualenv/virtualenv/discovery/py_info.py

@@ -124,6 +124,9 @@ def install_path(self, key):
             prefixes = self.prefix, self.exec_prefix, self.base_prefix, self.base_exec_prefix
             config_var = {k: "" if v in prefixes else v for k, v in self.sysconfig_vars.items()}
             result = self.sysconfig_path(key, config_var=config_var).lstrip(os.sep)
+        # A hack for https://github.com/pypa/virtualenv/issues/2208
+        if result.startswith(u"local/"):
+            return result[6:]
         return result
 
     @staticmethod