Merge pull request #5585 from radarhere/stdout

Catch OSError when checking if fp is sys.stdout

src/PIL/ImageFile.py

@@ -493,7 +493,11 @@ def _save(im, fp, tile, bufsize=0):
     # But, it would need at least the image size in most cases. RawEncode is
     # a tricky case.
     bufsize = max(MAXBLOCK, bufsize, im.size[0] * 4)  # see RawEncode.c
-    if fp == sys.stdout or (hasattr(sys.stdout, "buffer") and fp == sys.stdout.buffer):
+    try:
+        stdout = fp == sys.stdout or fp == sys.stdout.buffer
+    except (OSError, AttributeError):
+        stdout = False
+    if stdout:
         fp.flush()
         return
     try: