shelltest.od: abort correctly if 'cd ~' fails.

It seems 'set -e' doesn't quite work, in some shells, in that case.

Eric Kow wrote:
> I saw this warning, by the way:
> redo      t/shelltest
>   warning: 94
> cd: 271: can't cd to /opt/redo-0.05/t/space
> rmdir: failed to remove pace home dir': No such file or directory
>   warning: 111

t/shelltest.od

@@ -265,7 +265,7 @@ rm -f || fail 110
 	HOME="$PWD/space home dir"
 	rm -rf "$HOME"
 	mkdir "$HOME"
-	cd ~
+	cd ~ || exit 1
 	cd ..
 	rmdir 'space home dir'
 ) || warn 111