Fixing sdk gyp_vars mishandled in buildbot script.

The SDK has a dependency on an inner interface on the nacl side.
We use a fake to share code.
Updating the fake to actually provide what the nacl side expects.

BUG=None
TEST=trybots
R=sbc@chromium.org,binji@chromium.org

Review URL: https://codereview.chromium.org/575743006

Cr-Commit-Position: refs/heads/master@{#295148}

native_client_sdk/src/build_tools/buildbot_common.py

@@ -71,6 +71,9 @@ def GetWindowsEnvironment():
       return self.env[key]
 
     def __getitem__(self, key):
+      # The nacl side script now needs gyp_vars to return a list.
+      if key == 'gyp_vars':
+        return []
       return self.env[key]
 
     def SetEnv(self, key, value):
@@ -80,7 +83,6 @@ def GetWindowsEnvironment():
       self.env[key] = value
 
   context = FakeContext()
-  context['gyp_vars'] = []
   buildbot_standard.SetupWindowsEnvironment(context)
 
   # buildbot_standard.SetupWindowsEnvironment adds the directory which contains
@@ -97,7 +99,7 @@ def GetWindowsEnvironment():
   # KEY1=VALUE1\r\n
   # KEY2=VALUE2\r\n
   # ...
-  return dict(line.split('=') for line in stdout.split('\r\n')[:-1])
+  return dict(line.split('=', 1) for line in stdout.split('\r\n')[:-1])
 
 
 def BuildStep(name):