--- a/tests/test-import-merge.t	Sat May 19 18:51:14 2018 +0530
+++ b/tests/test-import-merge.t	Sat May 19 18:52:56 2018 +0530
@@ -143,7 +143,7 @@
   $ hg export 2 | head -7 > ../a.patch
   $ hg export tip > out
   >>> apatch = open("../a.patch", "ab")
-  >>> apatch.write("".join(open("out").readlines()[7:]))
+  >>> apatch.write(b"".join(open("out", 'rb').readlines()[7:])) and None
 
   $ cd ..
   $ hg clone -qr0 repo3 repo3-clone