untarring write-protected directories

[Guy Harris]

>Of course the "-o" flag will save you, but why leave an open hole for
>novice or BSD-acclimated users to trip into?

System V compatibility, presumably.  It wasn't SGI's idea, it was
AT&T's (V7, and thence BSD, disallowed giving files away - actually, it
dates back before V7; PWB/UNIX 1.0, and thence ... and thence S5, lets a
user give a file away); the most you can flame them for is not changing
"chown()" nor "tar", and if they had, somebody else would have flamed
them for incompatibility....

At least S5R4 lets you configure your system to disallow giving files
away (good idea, given that its 4.3BSD file system supports quotas...).