Merge pull request #13976 from meeseeksmachine/auto-backport-of-pr-13973-on-v3.1.x

tacaswell · web-flow · commit e43c728e533c · 2019-04-17T08:50:02.000-04:00
Backport PR #13973 on branch v3.1.x (BUG: Ensure docstrings are not accessed with -OO)
diff --git a/lib/matplotlib/scale.py b/lib/matplotlib/scale.py
@@ -741,8 +741,10 @@ def scale_factory(scale, axis, **kwargs):
     if scale not in _scale_mapping:
         raise ValueError("Unknown scale type '%s'" % scale)
     return _scale_mapping[scale](axis, **kwargs)
-scale_factory.__doc__ = scale_factory.__doc__ % {
-    "names": ", ".join(get_scale_names())}
+
+if scale_factory.__doc__:
+    scale_factory.__doc__ = scale_factory.__doc__ % {
+        "names": ", ".join(get_scale_names())}
 
 
 def register_scale(scale_class):
