Comment 3 for bug 626233

After looking through the code, it seems that rubber is not correctly respecting the paths from Latex. Furthermore, because it sets BIBINPUTS and BSTINPUTS when dealing with Bibtex, there's an additional bug where if the directive bibtex.path is set, then Bibtex can no longer find bib files in the original directory.

The path bug for Bibtex can be easily fixed by appending a : to the end of the BIBINPUTS and BSTINPUTS path, which allows Bibtex to attempt to search the default paths (http://compgroups.net/comp.text.tex/bibtex-and-path-to-bib-file/1908161).

For rubber itself to find the system bib and bst files, kpsepath from Kpathsea (https://tug.org/texinfohtml/kpathsea.html#Path-searching, https://linux.die.net/man/1/kpsepath) can be used to get the system search paths, with some processing necessary to convert kpsepath's output into usable system paths.