Description of problem:
%setup tries to uncompress plain .tar with lzma, makig build fai

Version-Release number of selected component (if applicable):
rpm-4.4.2.3-0.1.rc1.x86_64

How reproducible:
Try to build this srpm on rawhide (large, contains non free (but ok in the US))
content:
http://www.hajnet.cz/soubory/ufoai/ufoai-data-2.2-1.fc8.src.rpm
  
Actual results:
Executing(%prep): /bin/sh -e /var/tmp/rpm-tmp.37421
+ umask 022
+ cd /usr/src/redhat/BUILD
+ LANG=C
+ export LANG
+ unset DISPLAY
+ cd /usr/src/redhat/BUILD
+ rm -rf ufoai-data-2.2
+ /bin/mkdir -p ufoai-data-2.2
+ cd ufoai-data-2.2
+ /usr/bin/lzma -dc /usr/src/redhat/SOURCES/ufoai-2.2-data.tar
/var/tmp/rpm-tmp.37421: line 32: /usr/bin/lzma: No such file or directory
+ tar -xf -
tar: This does not look like a tar archive
tar: Error exit delayed from previous errors
error: Bad exit status from /var/tmp/rpm-tmp.37421 (%prep)


Expected results:
Succeeded build