It sounds like something like this would be a good thing to have.
A few thoughts.
1. If the mtime or size changes, doesn't this necessarily mean that
ctime changes? In other words, isn't tar's current test for size growing
redundant? This test was added in commit
c455373e5b7fc3037ad9e4204ba6c6aac2faa10f dated Oct 14 21:11:27 2006
+0000 but it's not clear to me why it is needed now.
2. How about a simpler option which basically says: warn only about
changes to any of the following: st_mtime, st_uid, st_gid, st_mode,
st_size. It's not clear that the extra complexity of a more-complicated
option is worth the aggravation.
