Backport PR #17882: Fix FFMpegBase.isAvailable with detached terminals.

dstansby · meeseeksmachine · commit 9cac5548279c · 2020-07-12T17:42:25.000Z
diff --git a/lib/matplotlib/animation.py b/lib/matplotlib/animation.py
@@ -597,7 +597,8 @@ def isAvailable(cls):
             # NOTE: when removed, remove the same method in AVConvBase.
             and b'LibAv' not in subprocess.run(
                 [cls.bin_path()], creationflags=subprocess_creation_flags,
-                stdout=subprocess.DEVNULL, stderr=subprocess.PIPE).stderr)
+                stdin=subprocess.DEVNULL, stdout=subprocess.DEVNULL,
+                stderr=subprocess.PIPE).stderr)
 
 
 # Combine FFMpeg options with pipe-based writing
