diff -r d77c3b023393 -r f659a407e5ee mercurial/hg.py
--- a/mercurial/hg.py	Sat Mar 03 23:49:39 2018 -0500
+++ b/mercurial/hg.py	Sun Mar 04 22:37:41 2018 +0530
@@ -269,7 +269,7 @@
             # ValueError is raised on Windows if the drive letters differ on
             # each path
             raise error.Abort(_('cannot calculate relative path'),
-                              hint=str(e))
+                              hint=util.forcebytestr(e))
     else:
         requirements += 'shared\n'