test-rename-merge2: fix test failure on Windows stable

test-rename-merge2: fix test failure on Windows

Windows and OpenVMS use double quote for shell quoting, posix uses
single quote. Since the other test lines added in 5668202cfaaf don't
include the quotes, this was presumably an oversight.

--- a/tests/test-rename-merge2.t	Fri Apr 17 12:11:14 2015 -0400
+++ b/tests/test-rename-merge2.t	Fri Apr 17 12:39:55 2015 -0400
@@ -100,7 +100,7 @@
   picked tool 'python ../merge' for rev (binary False symlink False)
   merging rev
   my rev@e300d1c794ec+ other rev@4ce40f5aca24 ancestor rev@924404dff337
-  launching merge tool: python ../merge $TESTTMP/t/t/rev '*' '*' (glob)
+  launching merge tool: python ../merge $TESTTMP/t/t/rev * * (glob)
   merge tool returned: 0
   0 files updated, 2 files merged, 0 files removed, 0 files unresolved
   (branch merge, don't forget to commit)