Revert of Simplify the initialization of Git objects in Host.

third_party/WebKit/Tools/Scripts/webkitpy/common/host_mock.py

 # Copyright (C) 2011 Google Inc. All rights reserved.
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #    * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
 #    * Redistributions in binary form must reproduce the above
 # copyright notice, this list of conditions and the following disclaimer
@@ skipping 24 matching lines @@
 # New-style ports need to move down into webkitpy.common.
 from webkitpy.layout_tests.builder_list import BuilderList
 from webkitpy.layout_tests.port.factory import PortFactory
 from webkitpy.layout_tests.port.test import add_unit_tests_to_mock_filesystem
 
 
 class MockHost(MockSystemHost):
 
     def __init__(self,
                  log_executive=False,
+                 initialize_scm_by_default=True,
                  web=None,
                  scm=None,
                  os_name=None,
                  os_version=None,
                  time_return_val=123):
         super(MockHost, self).__init__(
             log_executive=log_executive,
             os_name=os_name,
             os_version=os_version,
             time_return_val=time_return_val)
 
         add_unit_tests_to_mock_filesystem(self.filesystem)
         self.web = web or MockWeb()
+
         self._scm = scm
-
+        # TODO(qyearsley): we should never initialize the SCM by default, since
+        # the real object doesn't either. This has caused at least one bug
+        # (see bug 89498).
+        if initialize_scm_by_default:
+            self.initialize_scm()
         self.buildbot = MockBuildBot()
 
         # Note: We're using a real PortFactory here.  Tests which don't wish to depend
         # on the list of known ports should override this with a MockPortFactory.
         self.port_factory = PortFactory(self)
 
         self.builders = BuilderList(BUILDERS)
 
-    def scm(self, path=None):
-        if path:
-            return MockGit(cwd=path, filesystem=self.filesystem, executive=self.executive)
+    def initialize_scm(self, patch_directories=None):
         if not self._scm:
             self._scm = MockGit(filesystem=self.filesystem, executive=self.executive)
         # Various pieces of code (wrongly) call filesystem.chdir(checkout_root).
         # Making the checkout_root exist in the mock filesystem makes that chdir not raise.
         self.filesystem.maybe_make_directory(self._scm.checkout_root)
+
+    def scm(self):
         return self._scm
+
+    def scm_for_path(self, path):
+        # FIXME: consider supporting more than one SCM so that we can do more comprehensive testing.
+        self.initialize_scm()
+        return self._scm