Hi,

The attached patch is fixing a rather annoying problem when
org-latex-pdf-process is set to a list. Currently, only output of the
last command in the list is preserved in *Org PDF LaTeX output* buffer,
which sometimes prevents ox-latex from detecting compilation warnings.

ox-latex relies on *Org PDF LaTeX output* to contain the output of latex
compiler. However, unless the last command in the org-latex-pdf-process
is something like pdflatex, the compiler errors are erased by
`shell-command' called by `org-compile-file'.

Best,
Ihor