texmath-0.6.7: tests/writers/munder-04.tex
\underset{\mathrm{bottom}}{\mathrm{middle}}=\underset{\mathrm{bottom}}{\overset{\phantom{\mathrm{fail}}}{\mathrm{middle}}}\underset{\mathrm{bottom}}{\mathrm{middle}}=\underset{\mathrm{bottom}}{\overset{\phantom{\mathrm{fail}}}{\mathrm{middle}}}