Bah! Something stupid here, then. Thanks for checking.
/Checks carry on here
OK. The iso I have seems to be broken for sqlite, and that only AFAICT.
Today's download works - explodes so I can grab the libs :-/.
For the record, the exact error (with cp) was
bash-4.2$ explodepkg /mnt/tmp/slackware/ap/sqlite-3.7.13-i486-1.txz
Exploding package /mnt/tmp/slackware/ap/sqlite-3.7.13-i486-1.txz in current directory:
cat: /mnt/tmp/slackware/ap/sqlite-3.7.13-i486-1.txz: Input/output error
xz: (stdin): File format not recognized
The last line also was the error on the downloads.