DUrole fallthrough removed in docutils 0.14, causes inline code to fail in captions

[mpacer]

For "custom" roles that are not explicitly defined, when they are hit inside of a protected context (like in a caption, for example) LaTeX will err because it hasn't been explicitly defined.

\providecommand*{\DUrole}[2]{%
  % backwards compatibility: try \docutilsrole#1{#2}
  \ifcsname docutilsrole#1\endcsname%
    \csname docutilsrole#1\endcsname{#2}%
  \else
    \csname DUrole#1\endcsname{#2}%
  \fi%
}

It used to fallback on passing through the relevant value.

% inline markup (custom roles)
% \DUrole{#1}{#2} tries \DUrole#1{#2}
\providecommand*{\DUrole}[2]{%
  \ifcsname DUrole#1\endcsname%
    \csname DUrole#1\endcsname{#2}%
  \else% backwards compatibility: try \docutilsrole#1{#2}
    \ifcsname docutilsrole#1\endcsname%
      \csname docutilsrole#1\endcsname{#2}%
    \else%
      #2%
    \fi%
  \fi%
}

This is why

:code:`my inline code`

inside of a caption for a classed figure, like

.. figure:: figure1.png
   :align: center
   :figclass: w

   This is a wide figure, specified by adding "w" to the figclass.  It is also
   center aligned, by setting the align keyword (can be left, right or center).
   This caption also has :code:`chunk of code`.

will cause our builds to fail when using docutils 0.14.