Merge branch 'jk/tests-timestamp-fix' into master

The test framework has been updated so that most tests will run
with predictable (artificial) timestamps.

* jk/tests-timestamp-fix:
  t9100: stop depending on commit timestamps
  test-lib: set deterministic default author/committer date
  t9100: explicitly unset GIT_COMMITTER_DATE
  t5539: make timestamp requirements more explicit
  t9700: loosen ident timezone regex
  t6000: use test_tick consistently

t/t9100-git-svn-basic.sh

@@ -200,8 +200,9 @@ GIT_SVN_ID=alt
 export GIT_SVN_ID
 test_expect_success "$name" \
     'git svn init "$svnrepo" && git svn fetch &&
-     git rev-list --pretty=raw remotes/git-svn | grep ^tree | uniq > a &&
-     git rev-list --pretty=raw remotes/alt | grep ^tree | uniq > b &&
+     git log --format="tree %T %s" remotes/git-svn |
+	awk "!seen[\$0]++ { print \$1, \$2 }" >a &&
+     git log --format="tree %T" alt >b &&
      test_cmp a b'
 
 name='check imported tree checksums expected tree checksums'