The file texinfo-4.13-lzip.tar.lz is an update adding lzip support to
http://ftp.gnu.org/gnu/texinfo/texinfo-4.13a.tar.gz. The changes with
respect to texinfo-4.13a are minimal (the diff is 166 lines long).

If anybody is interested, I have made a broader update that in addition
to lzip support also fixes quoting in the creation of info and html
files ('like this' instead of `like this'), uses the '.texi' extension
for texinfo files instead of '.txi' (as recommended by automake), adds
'-V' as synonym of '--version' to the info reader, removes the
dependency on pure decompressors (gunzip, bunzip2), and fixes some
warnings with modern gcc.

A sample of the output of the patched makeinfo can be seen at
http://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html