tests: fix test-casefolding.t
The message had changed, but the test was not updated. This test does not
run on Linux, but failed on my Mac.
--- a/tests/test-casefolding.t Wed Oct 19 15:07:11 2016 -0700
+++ b/tests/test-casefolding.t Fri Oct 21 16:31:16 2016 +0100
@@ -51,7 +51,8 @@
$ echo b > D/b
$ hg ci -Am addb D/b
$ hg mv D/b d/b
- D/b: not overwriting - file exists
+ D/b: not overwriting - file already committed
+ (hg rename --force to replace the file by recording a rename)
$ hg mv D/b d/c
$ hg st
A D/c