tar fails when reading from a pipe. The following example first creates a
small compressed tar file, and proceeds to display the error:

# make test archive
# file1 and file2 are just some files
tar zcf test.tgz file1 file2

# this is the error
cat test.tgz | tar tvzf -

On my i810 celeron 633, this last command newer finishes. However, "tar
tvfz test.tgz" works as excepted.

Of course, letting tar read from a pipe works on older Red Hat releases.