(\doprintindex): Change catcode of @ before \read, in case of

\initial{@} being the line that is read.
Reported by: Drew Csillag <drew_csillag@geocities.com>

texinfo.tex

@@ -2539,6 +2539,11 @@ width0pt\relax} \fi
   \indexbreaks
   %
   % See if the index file exists and is nonempty.
+  % Change catcode of @ here so that if the index file contains
+  % \initial {@}
+  % as its first line, TeX doesn't complain about mismatched braces
+  % (because it thinks @} is a control sequence).
+  \catcode`\@ = 11
   \openin 1 \jobname.#1s
   \ifeof 1
     % \enddoublecolumns gets confused if there is no text in the index,
@@ -2560,7 +2565,6 @@ width0pt\relax} \fi
       % to make right now.
       \def\indexbackslash{\rawbackslashxx}%
       \catcode`\\ = 0
-      \catcode`\@ = 11
       \escapechar = `\\
       \begindoublecolumns
       \input \jobname.#1s