git cl: allow to forcibly bypass cache and fetch CL description.

R=kbr@chromium.org
BUG=633572,688765

Change-Id: I2ce6530148bc2f00fe9f6a80aaccc520c69a2f83
Reviewed-on: https://chromium-review.googlesource.com/439186
Commit-Queue: Andrii Shyshkalov <tandrii@chromium.org>
Reviewed-by: Kenneth Russell <kbr@chromium.org>
diff --git a/git_cl.py b/git_cl.py
index c860d88..539ed1d 100755
--- a/git_cl.py
+++ b/git_cl.py
@@ -1355,8 +1355,8 @@
       return None
     return '%s/%s' % (self._codereview_impl.GetCodereviewServer(), issue)
 
-  def GetDescription(self, pretty=False):
-    if not self.has_description:
+  def GetDescription(self, pretty=False, force=False):
+    if not self.has_description or force:
       if self.GetIssue():
         self.description = self._codereview_impl.FetchDescription()
       self.has_description = True