tests: use unbundle in test-symlink-os-yes-fs-no.py The test (which should probably be rewritten as a .t test - the test was initially authored in 2009 and this may have predated some test harness features allowing us to implement it as a .t test) is verifying symlink behavior with regards to working directory operations. How it pulls bundle data into a repo is not relevant. So we can switch from pull to unbundle so we can support environments where bundlerepos don't work. Differential Revision: https://phab.mercurial-scm.org/D3111