Merge branch 'fc/transport-helper-waitpid' into pu

* fc/transport-helper-waitpid:
  transport-helper: check if remote helper is alive
  run-command: add new check_command helper
Merge branch 'jk/rm-removed-paths' into pu

* jk/rm-removed-paths:
  t3600: test rm of path with changed leading symlinks
  t3600: test behavior of reverse-d/f conflict
  rm: do not complain about d/f conflicts during deletion