[SCM tests] Don't forget to change back to original cwd.

After removing the temporary SCM directory change back to the
original cwd. This will avoid errors on future os.cwd() calls.

BUG=412774
TEST=test-webkitpy --all

Review URL: https://codereview.chromium.org/558103003

git-svn-id: svn://svn.chromium.org/blink/trunk@181894 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Tools/Scripts/webkitpy/common/checkout/scm/scm_unittest.py

@@ -155,6 +155,7 @@ class SCMTestBase(unittest.TestCase):
         self._svn_commit('add trunk')
 
         self._rmtree(svn_checkout_path)
+        self._chdir(self.original_cwd)
 
         self._set_up_svn_test_commits(svn_repo_url + "/trunk")
         return svn_repo_path
@@ -197,6 +198,7 @@ class SCMTestBase(unittest.TestCase):
         # svn does not seem to update after commit as I would expect.
         self._run(['svn', 'update'])
         self._rmtree(svn_checkout_path)
+        self._chdir(self.original_cwd)
 
     def _tear_down_svn_checkout(self):
         self._rmtree(self.temp_directory)