clone: print bookmark name when clone activates a bookmark Similar to the message that prints the checked out branch name. Without this, the user might accidentally move the @ bookmark.

clone: activate @ bookmark if updating to it The message "updating bookmark @ failed!" in test-bookmarks-pushpull.t is correct, because the changeset that the @ bookmark points to is not pushed to the target repository.

test-clone.t: check that branch "@" is not automatically checked out This verifies that c9339efed653 fixes the second problem mentioned in issue3677.

test-bookmarks.t: check that bookmark "default" is not automatically checked out This verifies that c9339efed653 fixes the problem originally reported in issue3677.