Fix #777 (part I): Latex output "too deeply nested"

Use \trivlist in Sphinx Verbatim.

sphinx/texinputs/sphinx.sty

@@ -341,20 +341,19 @@
   % - if caption: vertical space above caption = (\abovecaptionskip + D) with
   %   D = \baselineskip-\FrameHeightAdjust, and then \smallskip above frame.
   % - if no caption: (\smallskip + D) above frame. By default D=6pt.
-  \list{}{%
-  \setlength\parskip{0pt}%
-  \setlength\itemsep{0ex}%
-  \setlength\topsep{0ex}%
-  \setlength\parsep{0pt}% let's not forget this one!
-  \setlength\partopsep{0pt}%
-  \setlength\leftmargin{0pt}%
-  }%
-  \item
+  % Use trivlist rather than list to avoid possible "too deeply nested" error.
+  \itemsep   \z@skip
+  \topsep    \z@skip
+  \partopsep \z@skip% trivlist will set \parsep to \parskip = zero (see above)
+  % \leftmargin will be set to zero by trivlist
+  \rightmargin\z@
+  \parindent  \z@% becomes \itemindent. Default zero, but perhaps overwritten.
+  \trivlist\item\relax
   % use a minipage if we are already inside a framed environment
-  \relax\ifSphinx@inframed\noindent\begin{minipage}{\linewidth}\fi
+     \ifSphinx@inframed\noindent\begin{minipage}{\linewidth}\fi
      \MakeFramed {% adapted over from framed.sty's snugshade environment
-    \advance\hsize-\width\@totalleftmargin\z@\linewidth\hsize
-    \@setminipage  }%
+     \advance\hsize-\width\@totalleftmargin\z@\linewidth\hsize
+     \@setminipage  }%
      \small
      % For grid placement from \strut's in \FancyVerbFormatLine
      \lineskip\z@skip
@@ -365,8 +364,7 @@
   \endOriginalVerbatim
   \par\unskip\@minipagefalse\endMakeFramed
   \ifSphinx@inframed\end{minipage}\fi
-  \endlist
-  % LaTeX environments always revert local changes on exit, here e.g. \parskip
+  \endtrivlist
 }
 
 % define macro to frame contents and add shadow on right and bottom