tests: fix backslashes in test-casefolding

tests/test-casefolding.t

@@ -161,8 +161,8 b' issue 4481: revert across case only rena'
   $ echo 'foo' > a/B/c/D/E
   $ hg ci -m 'e content change'
   $ hg revert --all -r 0
-  removing a\B\c\D\E
-  adding a\B\c\D\e
+  removing a/B/c/D/E (glob)
+  adding a/B/c/D/e (glob)
   $ find * | sort
   a
   a/B