[Bug-tar] tar 1.31 aborts when extracting archive containing ./ with -U

[Harald van Dijk]

Hi,

After upgrading to GNU tar 1.31, I am seeing bad behaviour trying to 
extract archives containing ./ entries with the -U option. This is 
easily reproducible:

  $ tar cf - --no-recursion . | tar xUf -
  Aborted

The abort() in src/extract.c's maybe_recoverable(), marked with a 
comment as unreachable, is in fact reachable in this case.

Either giving an error on the failure to remove ./ (and continuing 
extraction of the remaining files in the archive) or silently accepting 
the ./ entry would work. GNU tar 1.30 silently accepted it.

Background: I'm using a modified version of Slackware's pkgtools to 
manage the software on my system. Its packages are tar archives 
containing ./ entries as part of the spec, and it extracts them using 
-U, ignoring errors, to handle upgrades better, especially in the case 
where an older version of the package provided a symlink where the newer 
provides a directory.

Cheers,
Harald van Dijk