Merge branch 'fixup-instruction' into pu

* branch fixup-instruction:
  Add a "fixup" instruction

The basic functionality is simple and working, but the --status output
is more interesting and I'm not convinced the current heuristic is
sufficiently robust.  The implementation in status_fixup could also
use some refactoring.
Merge branch 'skip-option' into pu

* branch skip-option:
  WIP
  Add --skip option

Needs more work to be able to handle "branch not found".