[Dvipng] Different image dimensions between dvipng 1.14 and 1.15

[Markus Triska]

Dear maintainers,

thank you for dvipng! To reproduce the issue, please download render.dvi:

    https://www.metalevel.at/ei/render.dvi

and then use:

    $ dvipng -T tight -D 300 -o render.png render.dvi && identify render.png

With dvipng 1.15, I get:

    This is dvipng 1.15 Copyright 2002-2015 Jan-Ake Larsson
    [1] 
    render.png PNG 505x41 505x41+0+0 8-bit sRGB 16c 2103B 0.000u 0:00.009

Whereas with dvipng 1.14, I got:

    This is dvipng 1.14 Copyright 2002-2010 Jan-Ake Larsson
    [1] 
    render.png PNG 505x43 505x43+0+0 8-bit sRGB 16c 2.1KB 0.000u 0:00.000

Please note that the resulting image dimensions now differ. In
particular, the height of this image (and others like it) has changed,
in this case from 43 (with version 1.14) to 41 (with version 1.15).

I use dvipng in a pixel-based layout application, and this difference
between versions adversely affects the layout of resulting documents.

Is there anything I can do to consistently obtain the exact same
results from version 1.14 also in newer versions?

For completeness, the TeX source of the file (render.tex) is:

    \documentclass{article}
    \thispagestyle{empty}
    \begin{document}
    $\delta: Q\times\Gamma \rightarrow Q\times\Gamma\times\{L,R\}$
    \end{document}

However, the DVI file alone suffices to reproduce the issue.

Thank you and all the best!
Markus