wptserve: Do not drop environment variables on running 'serve' command.

third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py

Index: third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py
diff --git a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py
index 861d0b0f44569acb6a1732b2713b024c2a16b999..7983f158d80c8db7a0930167b10d06713eb0eb58 100644
--- a/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py
+++ b/third_party/WebKit/Tools/Scripts/webkitpy/layout_tests/servers/wptserve.py
@@ -4,6 +4,8 @@
 
 """Start and stop the WPTserve servers as they're used by the layout tests."""
 
+import os
+
 from webkitpy.layout_tests.servers import server_base
 
 
@@ -48,7 +50,8 @@ class WPTServe(server_base.ServerBase):
             self._stdout = self._stderr = self._executive.DEVNULL
         # TODO(burnik): We should stop setting the CWD once WPT can be run without it.
         self._cwd = path_to_wpt_root
-        self._env = {'PYTHONPATH': path_to_thirdparty}
+        self._env = os.environ.copy()

[qyearsley, 2016/10/14 15:56:37]

Could you change this to:

  self._env = port_obj.host.environ.copy()

For real Host objects, this should be the same as os.environ, but accessing the
environment variables through host makes it easier to test.

[tkent, 2016/10/14 16:07:04]

Done.
I haven't tested Patch Set 2 on Windows.  A Windows machine is not available
just now.

+        self._env.update({'PYTHONPATH': path_to_thirdparty})
         self._keep_process_reference = True
         self._start_cmd = start_cmd