diff -r 8395fddde46c -r 9e2866065982 hgext/convert/subversion.py
--- a/hgext/convert/subversion.py	Sat Mar 03 09:50:07 2018 -0500
+++ b/hgext/convert/subversion.py	Sat Mar 03 21:01:07 2018 +0530
@@ -147,7 +147,7 @@
         # Caller may interrupt the iteration
         pickle.dump(None, fp, protocol)
     except Exception as inst:
-        pickle.dump(str(inst), fp, protocol)
+        pickle.dump(util.forcebytestr(inst), fp, protocol)
     else:
         pickle.dump(None, fp, protocol)
     fp.flush()