Put the choice of JSON encoder for Eliot into its own module

and use it in a few places

src/allmydata/test/__init__.py

@@ -125,5 +125,5 @@ if sys.platform == "win32":
     initialize()
 
 from eliot import to_file
-from allmydata.util.jsonbytes import AnyBytesJSONEncoder
-to_file(open("eliot.log", "wb"), encoder=AnyBytesJSONEncoder)
+from allmydata.util.eliotutil import eliot_json_encoder
+to_file(open("eliot.log", "wb"), encoder=eliot_json_encoder)

src/allmydata/test/test_eliotutil.py

@@ -65,11 +65,11 @@ from twisted.internet.task import deferLater
 from twisted.internet import reactor
 
 from ..util.eliotutil import (
+    eliot_json_encoder,
     log_call_deferred,
     _parse_destination_description,
     _EliotLogging,
 )
-from ..util.jsonbytes import AnyBytesJSONEncoder
 
 from .common import (
     SyncTestCase,
@@ -118,7 +118,7 @@ class ParseDestinationDescriptionTests(SyncTestCase):
         reactor = object()
         self.assertThat(
             _parse_destination_description("file:-")(reactor),
-            Equals(FileDestination(stdout, encoder=AnyBytesJSONEncoder)),
+            Equals(FileDestination(stdout, encoder=eliot_json_encoder)),
         )
 
 

src/allmydata/util/_eliot_updates.py

@@ -0,0 +1,28 @@
+"""
+Bring in some Eliot updates from newer versions of Eliot than we can
+depend on in Python 2.
+
+Every API in this module (except ``eliot_json_encoder``) should be obsolete as
+soon as we depend on Eliot 1.14 or newer.
+
+Ported to Python 3.
+"""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+from __future__ import unicode_literals
+
+from future.utils import PY2
+if PY2:
+    from builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, bytes, dict, list, object, range, str, max, min  # noqa: F401
+
+from .jsonbytes import AnyBytesJSONEncoder
+
+# There are currently a number of log messages that include non-UTF-8 bytes.
+# Allow these, at least for now.  Later when the whole test suite has been
+# converted to our SyncTestCase or AsyncTestCase it will be easier to turn
+# this off and then attribute log failures to specific codepaths so they can
+# be fixed (and then not regressed later) because those instances will result
+# in test failures instead of only garbage being written to the eliot log.
+eliot_json_encoder = AnyBytesJSONEncoder

src/allmydata/util/eliotutil.py

@@ -87,8 +87,9 @@ from twisted.internet.defer import (
 )
 from twisted.application.service import Service
 
-from .jsonbytes import AnyBytesJSONEncoder
-
+from ._eliot_updates import (
+    eliot_json_encoder,
+)
 
 def validateInstanceOf(t):
     """
@@ -306,7 +307,7 @@ class _DestinationParser(object):
                     rotateLength=rotate_length,
                     maxRotatedFiles=max_rotated_files,
                 )
-        return lambda reactor: FileDestination(get_file(), AnyBytesJSONEncoder)
+        return lambda reactor: FileDestination(get_file(), eliot_json_encoder)
 
 
 _parse_destination_description = _DestinationParser().parse