vcs-svn: Check for errors from open()

test-svn-fe segfaults when passed a bogus path.  Simplify debugging by
exiting with a meaningful error message instead.

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

test-svn-fe.c

@@ -9,7 +9,8 @@ int main(int argc, char *argv[])
 {
 	if (argc != 2)
 		usage("test-svn-fe <file>");
-	svndump_init(argv[1]);
+	if (svndump_init(argv[1]))
+		return 1;
 	svndump_read(NULL);
 	svndump_deinit();
 	svndump_reset();