test-init: replace 'echo -n' with 'printf'
The '-n' argument to echo is a non-standard extension that isn't
supported on Mac OS X 10.6.
% setup
adding a
new tip: 553596fad57b
% test that new changesets are visible to repo.lookup()
new tip: 799ae3599e0e
changeset: 1:799ae3599e0e
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: one more commit to demonstrate the bug