py3: conditionalize some LFS test output

I'm not sure why the one stackframe is py2 only, but that seems harmless.  The
remaining failure is LfsCorruptionError printing the fully qualified name, as
well as b'' around its message.

tests/test-lfs-serve-access.t

@@ -340,13 +340,13 b' Test a checksum failure during the proce'
   $LOCALIP - - [$ERRDATE$] HG error:  Traceback (most recent call last): (glob)
   $LOCALIP - - [$ERRDATE$] HG error:      verifies = store.verify(oid) (glob)
   $LOCALIP - - [$ERRDATE$] HG error:      raise IOError(errno.EIO, r'%s: I/O error' % oid.decode("utf-8")) (glob)
-  $LOCALIP - - [$ERRDATE$] HG error:  IOError: [Errno 5] f03217a32529a28a42d03b1244fe09b6e0f9fd06d7b966d4d50567be2abe6c0e: I/O error (glob)
+  $LOCALIP - - [$ERRDATE$] HG error:  *Error: [Errno 5] f03217a32529a28a42d03b1244fe09b6e0f9fd06d7b966d4d50567be2abe6c0e: I/O error (glob)
   $LOCALIP - - [$ERRDATE$] HG error:   (glob)
   $LOCALIP - - [$ERRDATE$] HG error:  Exception happened while processing request '/.git/info/lfs/objects/batch': (glob)
   $LOCALIP - - [$ERRDATE$] HG error:  Traceback (most recent call last): (glob)
   $LOCALIP - - [$ERRDATE$] HG error:      verifies = store.verify(oid) (glob)
   $LOCALIP - - [$ERRDATE$] HG error:      raise IOError(errno.EIO, r'%s: I/O error' % oid.decode("utf-8")) (glob)
-  $LOCALIP - - [$ERRDATE$] HG error:  IOError: [Errno 5] b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c: I/O error (glob)
+  $LOCALIP - - [$ERRDATE$] HG error:  *Error: [Errno 5] b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c: I/O error (glob)
   $LOCALIP - - [$ERRDATE$] HG error:   (glob)
   $LOCALIP - - [$ERRDATE$] HG error:  Exception happened while processing request '/.hg/lfs/objects/b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c': (glob)
   $LOCALIP - - [$ERRDATE$] HG error:  Traceback (most recent call last): (glob)
@@ -362,12 +362,12 b' Test a checksum failure during the proce'
       for chunk in self.server.application(env, self._start_response):
       for r in self._runwsgi(req, res, repo):
       rctx, req, res, self.check_perm)
-      return func(*(args + a), **kw)
+      return func(*(args + a), **kw) (no-py3 !)
       lambda perm:
       res.setbodybytes(localstore.read(oid))
       blob = self._read(self.vfs, oid, verify)
       raise IOError(errno.EIO, r'%s: I/O error' % oid.decode("utf-8"))
-  IOError: [Errno 5] 276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d: I/O error
+  *Error: [Errno 5] 276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d: I/O error (glob)
   
   $LOCALIP - - [$ERRDATE$] HG error:  Exception happened while processing request '/.hg/lfs/objects/276f73cfd75f9fb519810df5f5d96d6594ca2521abd86cbcd92122f7d51a1f3d': (glob)
   $LOCALIP - - [$ERRDATE$] HG error:  Traceback (most recent call last): (glob)