--- a/build-aux/texinfo.tex	Sun Mar 10 17:09:30 2019 +0100
+++ b/build-aux/texinfo.tex	Sun Mar 10 10:11:53 2019 -0700
@@ -3,7 +3,7 @@
 % Load plain if necessary, i.e., if running under initex.
 \expandafter\ifx\csname fmtname\endcsname\relax\input plain\fi
 %
-\def\texinfoversion{2019-03-07.19}
+\def\texinfoversion{2019-03-09.13}
 
 %
 % Copyright 1985, 1986, 1988, 1990-2019 Free Software Foundation, Inc.
@@ -387,7 +387,7 @@
     % take effect in \write's, yet the group defined by the \vbox ends
     % before the \shipout runs.
     %
-    \indexdummies         % don't expand commands in the output.
+    \atdummies         % don't expand commands in the output.
     \turnoffactive
     \shipout\vbox{%
       % Do this early so pdf references go to the beginning of the page.
@@ -4852,23 +4852,8 @@
 \def\docodeindexxxx #1{\doind{\indexname}{\code{#1}}}
 
 
-% Used when writing an index entry out to an index file to prevent
-% expansion of Texinfo commands that can appear in an index entry.
-%
-\def\indexdummies{%
-  \definedummyletter\@%
-  \definedummyletter\ %
-  %
-  % For texindex which always views { and } as separators.
-  \def\{{\lbracechar{}}%
-  \def\}{\rbracechar{}}%
-  %
-  % Do the redefinitions.
-  \definedummies
-  \otherbackslash
-}
-
-% Used for the aux and toc files, where @ is the escape character.
+% Used for the aux, toc and index files to prevent expansion of Texinfo 
+% commands.
 %
 \def\atdummies{%
   \definedummyletter\@%
@@ -4898,8 +4883,7 @@
 \def\definedummyletter#1{\def#1{\string#1}}%
 \let\definedummyaccent\definedummyletter
 
-% Called from \indexdummies and \atdummies, to effectively prevent
-% the expansion of commands.
+% Called from \atdummies to prevent the expansion of commands.
 %
 \def\definedummies{%
   %
@@ -5212,8 +5196,6 @@
 
 
 
-\let\SETmarginindex=\relax % put index entries in margin (undocumented)?
-
 % #1 is the index name, #2 is the entry text.
 \def\doind#1#2{%
   \iflinks
@@ -5256,6 +5238,9 @@
   \xdef\indexsortkey{#1}\endgroup}
 }
 
+% The default definition
+\def\sortas#1{}%
+
 % Given index entry text like "aaa @subentry bbb @sortas{ZZZ}":
 %   * Set \bracedtext to "{aaa}{bbb}"
 %   * Set \fullindexsortkey to "aaa @subentry ZZZ"
@@ -5275,7 +5260,6 @@
     %
     % Fully expand the segment, throwing away any @sortas directives, and 
     % trim spaces.
-    \def\sortas##1{}%
     \edef\trimmed{\segment}%
     \edef\trimmed{\expandafter\eatspaces\expandafter{\trimmed}}%
     %
@@ -5317,19 +5301,20 @@
   \fi
 }
 \def\isfinish{\finish}%
+\newbox\dummybox % used above
 
 \let\subentry\relax
 
 % Write the entry in \toks0 to the index file.
 %
 \def\doindwrite{%
-  % Put the index entry in the margin if desired.
-  \ifx\SETmarginindex\relax\else
-    \insert\margin{\hbox{\vrule height8pt depth3pt width0pt \the\toks0}}%
-  \fi
-  %
-  % Remember, we are within a group.
-  \indexdummies % Must do this here, since \bf, etc expand at this stage
+  \maybemarginindex
+  %
+  \atdummies
+  %
+  % For texindex which always views { and } as separators.
+  \def\{{\lbracechar{}}%
+  \def\}{\rbracechar{}}%
   %
   % Split the entry into primary entry and any subentries, and get the index 
   % sort key.
@@ -5347,7 +5332,15 @@
   }%
   \temp
 }
-\newbox\dummybox % used above
+
+% Put the index entry in the margin if desired (undocumented).
+\def\maybemarginindex{%
+  \ifx\SETmarginindex\relax\else
+    \insert\margin{\hbox{\vrule height8pt depth3pt width0pt \relax\indextext}}%
+  \fi
+}
+\let\SETmarginindex=\relax
+
 
 % Take care of unwanted page breaks/skips around a whatsit:
 %
@@ -8048,33 +8041,17 @@
 % alias because \c means cedilla in @tex or @math
 \let\texinfoc=\c
 
-\newcount\savedcatcodeone
-\newcount\savedcatcodetwo
-
 % Used at the time of macro expansion.
 % Argument is macro body with arguments substituted
 \def\scanmacro#1{%
   \newlinechar`\^^M
   \def\xeatspaces{\eatspaces}%
   %
-  % Temporarily undo catcode changes of \printindex.  Set catcode of @ to
-  % 0 so that @-commands in macro expansions aren't printed literally when 
-  % formatting an index file, where \ is used as the escape character.
-  \savedcatcodeone=\catcode`\@
-  \savedcatcodetwo=\catcode`\\
-  \catcode`\@=0
-  \catcode`\\=\active
-  %
   % Process the macro body under the current catcode regime.
   \scantokens{#1@texinfoc}%
   %
-  \catcode`\@=\savedcatcodeone
-  \catcode`\\=\savedcatcodetwo
-  %
   % The \texinfoc is to remove the \newlinechar added by \scantokens, and
   % can be noticed by \parsearg.
-  %   We avoid surrounding the call to \scantokens with \bgroup and \egroup
-  % to allow macros to open or close groups themselves.
 }
 
 % Used for copying and captions