Created attachment 17625 [details]
test pdf

Bounding box calculations are not correct in 9.27.

example: latex file (pdf also attached)
-----
\documentclass{article}

\begin{document}

\thispagestyle{empty}

\[
\left[\sum_k L_k g_{1,k} b_{1,k}^*\right]
\]

\end{document}
-----

bounding box calculation:

gs -sDEVICE=bbox -dNOPAUSE -dBATCH test.pdf

result (9.26):
%%BoundingBox: 272 616 339 647

clipping by:
gs -sDEVICE=pdfwrite \                     
   -o trimmedFile.pdf \
   -c "[/CropBox [272 616 339 647] /PAGES pdfmark" \
   -f test.pdf

returns expected pdf with the content;

in 9.27, bounding box is wrong:

%%BoundingBox: 264 612 336 671

clipping as before leaves some parts of the equation out.