[Bug-cpio] Absolute filenames in copy-in

[J Martin Rushton]

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The documentation for cpio is currently seriously misleading,
particularly for those who have used the utility for many years.
Specifically in both the info page tutorial and in the bottom part of
the man page there is the claim:

- -------%<-------------
If you are  dealing  with  an archived directory tree, you need to use
the `-d' option to create directories as necessary, something like:

       % cpio -idv < tree.cpio

This  will  take  the  contents  of  the  archive tree.cpio and
extract it to the current directory.
- -------%<-------------

Please note the final few words.  For someone used to older version
(for instance that supplied with CentOS 5), this claim is correct.  A
dump of a filesystem will have the leading "/"s stripped off and the
tree built in the current directory.  Later versions do not do this
and I note that --absolute-filenames is marked as default.

I had retrieved a number of cpio from tape where each was a complete
dump of a root filesystem.  On one machine I used the above command to
expand the tree based on the current filesystem (as I have done many
times before) and it worked.  To speed things up I repeated the
command on one of the other nodes and it overwrote my CentOS 6.7
system with a CentOS 5.11 system.  As you can imagine the result was
an unbootable system.

Is it possible to update the documentation to warn about this change
in behaviour?  Quite apart from those updating from earlier versions,
the current documentation is internally inconsistent.
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