$NetBSD: patch-mozilla_build_moz.configure_init.configure,v 1.1 2018/12/16 08:29:48 ryoon Exp $

--- mozilla/build/moz.configure/init.configure.orig	2017-04-14 04:53:01.000000000 +0000
+++ mozilla/build/moz.configure/init.configure
@@ -134,6 +134,7 @@ option(env='PYTHON', nargs=1, help='Pyth
 @imports(_from='mozbuild.configure.util', _import='LineIO')
 @imports(_from='mozbuild.virtualenv', _import='VirtualenvManager')
 @imports(_from='mozbuild.virtualenv', _import='verify_python_version')
+@imports(_from='__builtin__', _import='KeyError')
 @imports('distutils.sysconfig')
 def virtualenv_python(env_python, build_env, mozconfig, help):
     if help:
@@ -153,6 +154,12 @@ def virtualenv_python(env_python, build_
             python = mozconfig['vars']['added']['PYTHON']
         elif 'PYTHON' in mozconfig['vars']['modified']:
             python = mozconfig['vars']['modified']['PYTHON'][1]
+        for i in ('env', 'vars'):
+            for j in ('added', 'modified'):
+                try:
+                    del mozconfig[i][j]['PYTHON']
+                except KeyError:
+                    pass
 
     with LineIO(lambda l: log.error(l)) as out:
         verify_python_version(out)
@@ -188,7 +195,10 @@ def virtualenv_python(env_python, build_
     if python != normsep(sys.executable):
         log.info('Reexecuting in the virtualenv')
         if env_python:
-            del os.environ['PYTHON']
+            try:
+                del os.environ['PYTHON']
+            except KeyError:
+                pass
         # One would prefer to use os.execl, but that's completely borked on
         # Windows.
         sys.exit(subprocess.call([python] + sys.argv))