git-codereview: fix TestReword on Windows

It wasn't caught by x/build's Windows builders because
they don't have git and skip these tests. But LUCI ones
do have git, and caught this.

For golang/go#46693.

Change-Id: I50f3b69909344f4657e5c737e3b434a2538e4939
Reviewed-on: https://go-review.googlesource.com/c/review/+/505895
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Dmitri Shuralyov <dmitshur@golang.org>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
diff --git a/git-codereview/reword_test.go b/git-codereview/reword_test.go
index e4ee817..7589d37 100644
--- a/git-codereview/reword_test.go
+++ b/git-codereview/reword_test.go
@@ -37,7 +37,7 @@
 	testMain(t, "reword", "MSG3", "MSG4")
 	testNoStdout(t)
 	testPrintedStderr(t, "editing messages (new texts logged in",
-		".git/REWORD_MSGS in case of failure)")
+		".git"+string(os.PathSeparator)+"REWORD_MSGS in case of failure)")
 
 	testMain(t, "pending", "-c", "-l", "-s")
 	testNoStderr(t)
@@ -51,7 +51,7 @@
 	testMain(t, "reword") // reword all
 	testNoStdout(t)
 	testPrintedStderr(t, "editing messages (new texts logged in",
-		".git/REWORD_MSGS in case of failure)")
+		".git"+string(os.PathSeparator)+"REWORD_MSGS in case of failure)")
 
 	testMain(t, "pending", "-c", "-l", "-s")
 	testNoStderr(t)