Merge us:git/staging/rsync-backup

* us:git/staging/rsync-backup:
  rsync-backup.in, rsync-backup.8: Trim caches on fshash mismatch.
  rsync-backup.in (run): Option to preserve standard input.
  fshash.in, fshash.1: Evict cache entries identified by diff files.

Conflicts:
	fshash.1

diff --cc fshash.1
index 51580b882e22aa4f9a1c56fa1fae7b82abd5379f,2ceb1750b16b39961b2d7b806383cf13d02acb08..788a7d847f1653f816b5d4d6129e111813a774ac
--- 1/fshash.1
--- 2/fshash.1
+++ b/fshash.1
@@@ -92,8 -100,16 +100,16 @@@ Use th
  .I hash
  function, which can be any hash function supported by Python's
  .BR hashlib .
 -If this option may be omitted then the hash is read from the cache file;
 -if there is no cache file either, then an error is reported.
 +This option may be omitted: if it is, then the hash is read from the
 +cache file; if there is no cache file either, then an error is reported.
+ .TP
+ .B \-u, \-\-udiff
+ Rather than produce a manifest, read a unified
+ .BR diff (1)
+ from standard input, and clear from the cache all files mentioned as
+ being different.  Filenames in the diff are considered relative to
+ .I dir ,
+ defaulting to the current working directory.
  .PP
  Positional arguments are interpreted as files and directories to be
  processed, in order.  A directory name which ends in