diff -r 5bc7ff103081 -r a00c38b33047 mercurial/scmutil.py
--- a/mercurial/scmutil.py	Sat Mar 10 15:57:16 2018 +0900
+++ b/mercurial/scmutil.py	Tue Mar 06 07:24:12 2018 -0600
@@ -689,7 +689,8 @@
                 continue
             from . import bookmarks # avoid import cycle
             repo.ui.debug('moving bookmarks %r from %s to %s\n' %
-                          (oldbmarks, hex(oldnode), hex(newnode)))
+                          (util.rapply(pycompat.maybebytestr, oldbmarks),
+                           hex(oldnode), hex(newnode)))
             # Delete divergent bookmarks being parents of related newnodes
             deleterevs = repo.revs('parents(roots(%ln & (::%n))) - parents(%n)',
                                    allnewnodes, newnode, oldnode)