Merge pull request #5131 from blueyed/_getfailureheadline

_getfailureheadline: get head_line property only once

src/_pytest/terminal.py

@@ -734,9 +734,9 @@ class TerminalReporter(object):
         return res + " "
 
     def _getfailureheadline(self, rep):
-        if rep.head_line:
-            return rep.head_line
-        else:
+        head_line = rep.head_line
+        if head_line:
+            return head_line
         return "test session"  # XXX?
 
     def _getcrashline(self, rep):