test-convert-cvs: make test compatible with chg The test uses the 'print' method instead of writing to stdout using 'ui.write' which leads to incompatibility with chg. This commit modifies the test to use the 'ui' object instead which fixes the problem. Test Plan: Ran the test 'test-convert-cvs.t' with and without '--chg' option. Differential Revision: https://phab.mercurial-scm.org/D923