Backport PR #16966: Fix animation writer fallback.

QuLogic · meeseeksmachine · commit a14050a9892b · 2020-03-30T22:20:53.000Z
diff --git a/lib/matplotlib/animation.py b/lib/matplotlib/animation.py
@@ -1099,7 +1099,7 @@ def func(current_frame: int, total_frames: int) -> Any
                                          extra_args=extra_args,
                                          metadata=metadata)
             else:
-                alt_writer = next(writers, None)
+                alt_writer = next(iter(writers), None)
                 if alt_writer is None:
                     raise ValueError("Cannot save animation: no writers are "
                                      "available. Please install ffmpeg to "
