The reason for this happening is that lua-posix changed its main module
name from posix_c to posix. The maintainers of the debian package missed
that and still install a symlink from
/usr/lib/x86_64-linux-gnu/lua/5.1/posix_c.so.
This can be seen in the output above (no file
'/usr/lib/x86_64-linux-gnu/lua/5.1/posix.so') which shows that a
posix.so is searched for.
The solution for the users is to create a symlink to that file: sudo ln
-s /usr/lib/x86_64-linux-gnu/lua/5.1/posix_c.so
/usr/lib/x86_64-linux-gnu/lua/5.1/posix.so
Or simply rename the posix_c.so to posix.so
WARNING: This has to be undone before upgrading after a fix from the
package maintainers gets released or the upgrade might fail.
The maintainers should fix that in the packages ASAP.
