graft: reuse --user and --date values in `hg graft --continue` (BC) Reading the user and date information from graftstate during `hg graft --continue` will help us in preserving the user and date arguments passed when `hg graft` was called. This patch reads that information and reuses that while running `hg graft --continue`. So after this patch, --user and --date values are preserved even if conflicts occur and user don't need to pass them again. The test changes demonstrate the fix. This is a backward incompatible change but I think of this more as a bug fix. Also thinking about removing the line from `hg help graft` which says --continue does not reapply other flags but need to check what are the other flags which needs to be preserved. Differential Revision: https://phab.mercurial-scm.org/D3659