test-hardlinks: add testcase for repo copied with 'cp -al' This patch adds a case to test-hardlinks.t which demonstrates that hardlinks in the working directory are broken up (using 'hg update'). Motivation for this patch: 'hg help clone' shows copying repositories *and* the working directory using 'cp -al', creating hardlinks in the *working directory* too (not just in the store). Note that we can't use 'cp -al' since for example MacOS X doesn't support these options on cp. I'm thus using the same trick as in test-hardlinks-safety.t for creating hardlinks in the working dir.