Status letters C and R are always followed by a score (denoting the
percentage of similarity between the source and target of the move or
-copy), and are the only ones to be so.
+copy). Status letter M may be followed by a score (denoting the
+percentage of dissimilarity) for file rewrites.
<sha1> is shown as all 0's if a file is new on the filesystem
and it is out of sync with the index.