Consistent behavior.

src/allmydata/test/common_util.py

@@ -12,6 +12,7 @@ if PY2:
     from future.builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, dict, list, object, range, str, max, min  # noqa: F401
 
 import os
+import sys
 import time
 import signal
 from random import randrange
@@ -85,7 +86,7 @@ def run_cli_native(verb, *args, **kwargs):
         bytes.
     """
     nodeargs = kwargs.pop("nodeargs", [])
-    encoding = kwargs.pop("encoding", None) or "utf-8"
+    encoding = kwargs.pop("encoding", None) or getattr(sys.stdout, "encoding") or "utf-8"
     return_bytes = kwargs.pop("return_bytes", False)
     verb = maybe_unicode_to_argv(verb)
     args = [maybe_unicode_to_argv(a) for a in args]

src/allmydata/util/encodingutil.py

@@ -256,7 +256,11 @@ def quote_output_u(*args, **kwargs):
     result = quote_output(*args, **kwargs)
     if isinstance(result, unicode):
         return result
-    return result.decode(kwargs.get("encoding", None) or io_encoding)
+    # Since we're quoting, the assumption is this will be read by a human, and
+    # therefore printed, so stdout's encoding is the plausible one. io_encoding
+    # is now always utf-8.
+    return result.decode(kwargs.get("encoding", None) or
+                         getattr(sys.stdout, "encoding") or io_encoding)
 
 
 def quote_output(s, quotemarks=True, quote_newlines=None, encoding=None):
@@ -287,7 +291,7 @@ def quote_output(s, quotemarks=True, quote_newlines=None, encoding=None):
     def _encode(s):
         if isinstance(s, bytes):
             try:
-                s = s.decode('utf-8')
+                s = s.decode("utf-8")
             except UnicodeDecodeError:
                 return b'b"%s"' % (ESCAPABLE_8BIT.sub(lambda m: _bytes_escape(m, quote_newlines), s),)