fix test

Author: tobiasdiez

src/sage/misc/abstract_method.py

@@ -194,7 +194,7 @@ def _sage_src_lines_(self):
             sage: src[0]
             'def version():\n'
             sage: lines
-            19
+            20
         """
         from sage.misc.sageinspect import sage_getsourcelines
         return sage_getsourcelines(self._f)