tar: Potential bug (?) when incremental archive selected - Deleting files in the target

Question

I have quite interesting observation which perhaps is a manifest of a bug.

My use case is to:

• take a backup of a folder, having a set of files from this folder added to --exclude-from file. I'm working with incremental backup (-g option set)
• on a new machine, restoring the tar to same location as on the original machine. Note, the new machine has already some files in the location; if anything exist, I want to replace / overwrite it.

Steps to reproduce

1. Create files and folders structure as below:

   /tmp/src
   └── etc
       ├── A.cfg
       └── config
           ├── 1.cfg
           ├── 2.cfg
           └── 3.cfg
   

2. Create exclude and include files

   mbp:tarTests jhartman$ cat /tmp/include.cfg
   /tmp/src/etc/
   mbp:tarTests jhartman$ cat /tmp/exclude.cfg
   /tmp/src/etc/config/*.cfg
   

3. Create an archive

   $ rm -f /tmp/snapshot 
   $ tar -g /tmp/snapshot -cvz -f /tmp/test.tar.gz -X /tmp/exclude.cfg -T /tmp/include.cfg
   
   
   ./tar-1.27/src/tar: /tmp/src/etc: Directory is new
   ./tar-1.27/src/tar: /tmp/src/etc/config: Directory is new
   ./tar-1.27/src/tar: Removing leading `/' from member names
   /tmp/src/etc/
   /tmp/src/etc/config/
   /tmp/src/etc/A.cfg
   

4. Un-archive to a new server. Before unarchiving, files in the new server:

   /tmp/src
   └── etc
       ├── A.cfg
       └── config
           ├── 3.cfg
           ├── 4.cfg
           └── 5.cfg
   

   • un-archive (on the target machine)

     $TAR_BASE/src/tar --overwrite --extract --force-local --listed-incremental=/dev/null --file /tmp/test.tar.gz -v -C /
     
     tmp/src/etc/
     tmp/src/etc/config/
     ./tar-1.30/src/tar: Deleting ‘tmp/src/etc/config/4.cfg’
     ./tar-1.30/src/tar: Deleting ‘tmp/src/etc/config/5.cfg’
     tmp/src/etc/A.cfg
     

So eventually, files in this folder:

/tmp/src
└── etc
    ├── A.cfg
    └── config
        └── 3.cfg

As you see, despite 4.cfg and 5.cfg were not int he src machine, they are gone. I'm guessing it's because of using /tmp/src/etc/config/*.cfg in the exclude file.

Worth to mention that this behaviour was changing across the versions: 1.30, 1.27, 1.27.1, 1.29 - NOK, 1.25, 1.26, 1.28 - OK (where NOK means - I could see Deleting message for the files in my concern).

What do you think?

Thank you, Jarek

Update, 2018-08-21, 20:51

Regardless of the version I run, output of the --list operation is same and shows D at the config folder:

tar --list --incremental --verbose --verbose --file /tmp/test.tar.gz

drwxr-xr-x jhartman/staff   16 2018-08-21 20:44 tmp/src/etc/
Y A.cfg
D config

drwxr-xr-x jhartman/staff   22 2018-08-21 20:44 tmp/src/etc/config/
N 1.cfg
N 2.cfg
N 3.cfg

-rw-r--r-- jhartman/staff   30 2018-08-21 20:44 tmp/src/etc/A.cfg

Update 21:03

For reference, scripts I've used for the tests are stored in https://github.com/jaroslawhartman/tar-tests repo.

See output.txt for detailed results of the tests.