Note that abspath() was added in 1.5.2.

Doc/lib/libposixpath.tex

@@ -12,6 +12,7 @@ This module implements some useful functions on pathnames.
 Return a normalized absolutized version of the pathname \var{path}.
 On most platforms, this is equivalent to
 \code{normpath(join(os.getcwd()), \var{path})}.
+\versionadded{1.5.2}
 \end{funcdesc}
 
 \begin{funcdesc}{basename}{path}