tests: synchronize the git and Mercurial username The problem with the default name of "test" set by the test runner is the stringutil methods are unable to split out separate user and email addresses that git wants. This means the username is recorded in git as "test <test>". Amending a commit with that user ends up trying to use "<test>" as the person field for the new commit, and the git library complains about the angle brackets. We should probably abort with a clearer message any time this bad form is used with the git extension. One of the commit dates is tweaked to recreate the ambiguous hash prefix from before. Differential Revision: https://phab.mercurial-scm.org/D10531