Fix docstring to be a docstring.

TBR=bradnelson

Review URL: http://codereview.chromium.org/2808062

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@53386 0039d316-1c4b-4281-b951-d872f2087c98

gclient.py

@@ -446,7 +446,7 @@ class Dependency(GClientKeywords):
     return '%s: %s' % (self.name, self.url)
 
   def hierarchy(self):
-    "Returns a human-readable hierarchical reference to a Dependency."
+    """Returns a human-readable hierarchical reference to a Dependency."""
     out = '%s(%s)' % (self.name, self.url)
     i = self.parent
     while i and i.name: