Bug 782847 - Pymake native commands don't pass the correct environmen…

…t to subprocesses. r=gps

This change is technically backwards incompatible, but it brings native command
behavior in line with subprocess behavior.

pymake/process.py

@@ -207,10 +207,13 @@ def __init__(self, module, method, argv, env, cwd, pycommandpath=None):
         self.pycommandpath = pycommandpath or []
 
     def run(self):
-        oldenv = os.environ
+        # os.environ is a magic dictionary. Setting it to something else
+        # doesn't affect the environment of subprocesses, so use clear/update
+        oldenv = dict(os.environ)
         try:
             os.chdir(self.cwd)
-            os.environ = self.env
+            os.environ.clear()
+            os.environ.update(self.env)
             if self.module not in sys.modules:
                 load_module_recursive(self.module,
                                       sys.path + self.pycommandpath)
@@ -240,7 +243,8 @@ def run(self):
                 print >>sys.stderr, traceback.print_exc()
                 return (e.code if isinstance(e.code, int) else 1)
         finally:
-            os.environ = oldenv
+            os.environ.clear()
+            os.environ.update(oldenv)
         return 0
 
 def job_runner(job):

tests/native-environment.mk

@@ -1,10 +1,11 @@
 #T gmake skip
 export EXPECTED := some data
 
-CMD = %pycmd writeenvtofile
 PYCOMMANDPATH = $(TESTPATH)
 
 all:
-	$(CMD) results EXPECTED
+	%pycmd writeenvtofile results EXPECTED
+	test "$$(cat results)" = "$(EXPECTED)"
+	%pycmd writesubprocessenvtofile results EXPECTED
 	test "$$(cat results)" = "$(EXPECTED)"
 	@echo TEST-PASS

tests/pycmd.py

@@ -1,4 +1,4 @@
-import os, sys
+import os, sys, subprocess
 
 def writetofile(args):
   with open(args[0], 'w') as f:
@@ -8,6 +8,15 @@ def writeenvtofile(args):
   with open(args[0], 'w') as f:
     f.write(os.environ[args[1]])
 
+def writesubprocessenvtofile(args):
+  with open(args[0], 'w') as f:
+    p = subprocess.Popen([sys.executable, "-c",
+                          "import os; print os.environ['%s']" % args[1]],
+                          stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    stdout, stderr = p.communicate()
+    assert p.returncode == 0
+    f.write(stdout)
+
 def convertasplode(arg):
   try:
     return int(arg)