xz-utils (4.999.9beta+20100212-2) unstable; urgency=low

  The tiny xzdec and lzmadec decompressors have been moved to the new
  xzdec package.  One can use xzcat (which is an abbreviation for
  “xz --decompress --stdout”) to replace them where space is not a
  premium.

 -- Jonathan Nieder <jrnieder@gmail.com>  Tue, 23 Feb 2010 08:24:10 -0600

xz-utils (4.999.9beta+20100117-1) unstable; urgency=low

  From this version on, xz produces sparse files by default when
  decompressing.  This saves disk space when reproducing files with long
  runs of zero bytes, such as file system images.  Implementing this
  feature requires seeking forward beyond the end of a file so that the
  operating system knows where to put in a hole.

  If you use xz --decompress to write to end of a file that is appended
  to at the same time by another process, this could cause concurrent
  output from the other command to be overwritten.  This is a rare and
  quite weird thing to do.  If you really want to do it, note that xz’s
  buffering strategy is not part of its documented interface; to safely
  interleave concurrent output from xz and another command, a
  construction such as

  	xz --decompress input.xz | dd ibs=1k obs=1k >> log

  would be needed to avoid unpredictable results.

 -- Jonathan Nieder <jrnieder@gmail.com>  Tue, 02 Feb 2010 15:51:37 -0600