[PATCH 07 of 10 py3] bundle2: obtain repr() of exception in a python3-safe way

[Augie Fackler]

# HG changeset patch
# User Augie Fackler <augie at google.com>
# Date 1500909551 14400
#      Mon Jul 24 11:19:11 2017 -0400
# Node ID 89d7a53b500a213396ab3c8e043a31dc5538ccaf
# Parent  4c1f4e109bf90a8352a25a6b45a80fabcac6306b
bundle2: obtain repr() of exception in a python3-safe way

This was exposed by other problems in bundle generation, but I'm not
sure how to test it for now.

diff --git a/mercurial/bundle2.py b/mercurial/bundle2.py
--- a/mercurial/bundle2.py
+++ b/mercurial/bundle2.py
@@ -1021,11 +1021,12 @@ class bundlepart(object):
             ui.debug('bundle2-generatorexit\n')
             raise
         except BaseException as exc:
+            bexc = pycompat.bytestr(exc)
             # backup exception data for later
             ui.debug('bundle2-input-stream-interrupt: encoding exception %s'
-                     % exc)
+                     % bexc)
             tb = sys.exc_info()[2]
-            msg = 'unexpected error: %s' % exc
+            msg = 'unexpected error: %s' % bexc
             interpart = bundlepart('error:abort', [('message', msg)],
                                    mandatory=False)
             interpart.id = 0