** Description changed:

  This was recently fixed in duplicity trunk.  But I'm filing a bug for
  paperwork purposes and for Ubuntu SRUs.
  
  [Impact]
  
  When restarting a backup, duplicity may accidentally skip the first 65k
  chunk of one of the source files.  This means that when it is restored,
  it will be incomplete/corrupted, resulting in data loss.
+ 
+ Note that symptoms of this bug are diverse and may look like:
+ assert len( patch_seq ) == 1, len( patch_seq )
+ or
+ assert first.difftype != "diff", patch_seq
+ or
+ librsync error 103 while in patch cycle
+ 
+ These are all different results from this root cause.  In all cases, it
+ is because chunks of files are missing in your backup.  There is nothing
+ we can do to get those chunks back.  But a related patch in duplicity
+ trunk will let you restore the rest of your files (instead of just
+ crashing halfway through a restore like 0.6.22 does).  So try duplicity
+ trunk to get a little progress from your broken backups.  And use
+ duplicity trunk for all future backups.
  
  [Test Case]
  
  Download and install the 'test1.sh' file attached to this bug report, and run 
it like 'sh test1.sh'.  If it prints the following line, the bug is present:
  Binary files /tmp/source/newfile and /tmp/restore/newfile differ
  
  Or, follow these manual steps:
  mkdir /tmp/source
  dd if=/dev/urandom of=/tmp/source/bigfile bs=1024 count=5000
  # This next command will intentionally fail after the second volume!
  duplicity full /tmp/source file:///tmp/backup --vol 1 --fail 2 --no-encryption
  mv /tmp/source/bigfile /tmp/source/newfile
  duplicity full /tmp/source file:///tmp/backup --no-encryption
  duplicity restore file:///tmp/backup /tmp/restore --no-encryption
  # This next line will say the files differ if the bug is present
  diff /tmp/source/newfile /tmp/restore/newfile
  
  [Regression Potential]
  
  It's a relatively small patch, only affecting the specific case of
  restarting a backup when the file we were in the middle of is no longer
  there.  I'd say minor regression potential.

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https://bugs.launchpad.net/bugs/1252484

Title:
  Possible data loss when restarting in the middle of a deleted file

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