bpo-39450 Stripped whitespace before parsing the docstring in TestCase.shortDescription (GH-18175)

diff --git a/Lib/unittest/case.py b/Lib/unittest/case.py
index fa64a6e..5e5d535 100644
--- a/Lib/unittest/case.py
+++ b/Lib/unittest/case.py
@@ -512,7 +512,7 @@
         the specified test method's docstring.
         """
         doc = self._testMethodDoc
-        return doc and doc.split("\n")[0].strip() or None
+        return doc.strip().split("\n")[0].strip() if doc else None
 
 
     def id(self):