test: prepare tests for removing date aliases In the next patch, I'm gonna removing the global command aliases that force the epoch date but some tests either fail or their output change after that. Instead I'm copying the needed aliases in the test files that will otherwise change. Update test-rebase-obsolete.t because a revision hash is based on the epoch date after a 'commit --amend' and the output will change after removing date aliases. Update test-subrepo-git.t as the git subrepo doesn't use traditional date mechanisms. I'm not sure that updating the git subrepo to support default-date make sense. Add the commit alias to the test in order for making it pass after removing the date aliases globally.