Fix FFMpegBase.isAvailable with detached terminals.

QuLogic · QuLogic · commit b445b97a7f39 · 2020-07-10T16:51:30.000-04:00
When checking for ffmpeg/libav, set stdin to /dev/null, otherwise the
process will sleep if Python is running with a detached terminal. And we
definitely don't want ffmpeg/libav to grab user input here.
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
