bpo-41497: Fix potential UnicodeDecodeError in dis CLI (GH-21757)

(cherry picked from commit a4084b9)

Co-authored-by: Konge <[email protected]>

Author: miss-islington

Lib/dis.py

@@ -542,7 +542,7 @@ def _test():
     import argparse
 
     parser = argparse.ArgumentParser()
-    parser.add_argument('infile', type=argparse.FileType(), nargs='?', default='-')
+    parser.add_argument('infile', type=argparse.FileType('rb'), nargs='?', default='-')
     args = parser.parse_args()
     with args.infile as infile:
         source = infile.read()

Misc/NEWS.d/next/Library/2020-08-07-06-06-29.bpo-41497.aBtsWz.rst

@@ -0,0 +1 @@
+Fix potential UnicodeDecodeError in dis module.