Log Message:
Update to 1.22.0. From the changelog:

- "flock" locks replaced with POSIX "fcntl" ones.  They \ 
could be more
  portable.
- "redo-depfix" command appeared, that traverses through all \ 
".redo"
  directories and their dependency files, checks if corresponding
  targets has the same content but different "ctime"/"mtime" \ 
values
  and rewrites dependencies with that updated inode information.
- With "$REDO_STOP_IF_MODIFIED=1" environment variable redo will stop
  and fail if it meet externally modified file.  By default user is
  only warned about it, but building continues for convenience.