Use inspect.cleandoc, not textwrap.dedent, to clean docstrings.

anntzer · anntzer · commit abecfdf60674 · 2018-09-18T23:13:00.000+02:00
The latter would fail if the first line is not indented, which occurs.
diff --git a/lib/matplotlib/cbook/deprecation.py b/lib/matplotlib/cbook/deprecation.py
@@ -1,5 +1,5 @@
 import functools
-import textwrap
+import inspect
 import warnings
 
 
@@ -215,7 +215,7 @@ def wrapper(*args, **kwargs):
             warnings.warn(message, category, stacklevel=2)
             return func(*args, **kwargs)
 
-        old_doc = textwrap.dedent(old_doc or '').strip('\n')
+        old_doc = inspect.cleandoc(old_doc or '').strip('\n')
         message = message.strip()
         new_doc = ('.. deprecated:: {since}\n'
                    '   {message}\n'
