py3: suppress the output of .write() calls in tests/test-revlog-v2.t

This makes the test pass on Python 3.

Differential Revision: https://phab.mercurial-scm.org/D3785

tests/test-revlog-v2.t

@@ -1,64 +1,64 b''
 #require reporevlogstore
 
 A repo with unknown revlogv2 requirement string cannot be opened
 
   $ hg init invalidreq
   $ cd invalidreq
   $ echo exp-revlogv2.unknown >> .hg/requires
   $ hg log
   abort: repository requires features unknown to this Mercurial: exp-revlogv2.unknown!
   (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
   [255]
   $ cd ..
 
 Can create and open repo with revlog v2 requirement
 
   $ cat >> $HGRCPATH << EOF
   > [experimental]
   > revlogv2 = enable-unstable-format-and-corrupt-my-data
   > EOF
 
   $ hg init empty-repo
   $ cd empty-repo
   $ cat .hg/requires
   dotencode
   exp-revlogv2.0
   fncache
   store
 
   $ hg log
 
 Unknown flags to revlog are rejected
 
   >>> with open('.hg/store/00changelog.i', 'wb') as fh:
-  ...     fh.write(b'\x00\x04\xde\xad')
+  ...     fh.write(b'\x00\x04\xde\xad') and None
 
   $ hg log
   abort: unknown flags (0x04) in version 57005 revlog 00changelog.i!
   [255]
 
   $ cd ..
 
 Writing a simple revlog v2 works
 
   $ hg init simple
   $ cd simple
   $ touch foo
   $ hg -q commit -A -m initial
 
   $ hg log
   changeset:   0:96ee1d7354c4
   tag:         tip
   user:        test
   date:        Thu Jan 01 00:00:00 1970 +0000
   summary:     initial
   
 Header written as expected (changelog always disables generaldelta)
 
   $ f --hexdump --bytes 4 .hg/store/00changelog.i
   .hg/store/00changelog.i:
   0000: 00 01 de ad                                     |....|
 
   $ f --hexdump --bytes 4 .hg/store/data/foo.i
   .hg/store/data/foo.i:
   0000: 00 03 de ad                                     |....|