This indeed looks like a fix to that issue, and I guess that it may be applied as is (only the texi2html.pl patch part the remaining doesn't make sense for texi2html).

Be aware that texi2html isn't maintained anymore, development has switched to a new implementation in texinfo, partly inspired by texi2html.

The texi2html 5.0 release, when built on x86_64-apple-darwin12 using the patch...

diff -uNr texi2html-5.0/test/many_input_files/tex_l2h.sh texi2html-5.0.fink/test/many_input_files/tex_l2h.sh
--- texi2html-5.0/test/many_input_files/tex_l2h.sh      2010-02-20 17:26:08.000000000 -0500
+++ texi2html-5.0.fink/test/many_input_files/tex_l2h.sh 2012-10-02 11:04:44.000000000 -0400
@@ -18,7 +18,7 @@
 echo "$basename" > $logfile
 : > $stdout_file
 
-if tmp_dir=`mktemp -p /tmp -d l2h_t2h_XXXXXXXX`; then
+if tmp_dir=`mktemp -d l2h_t2h_XXXXXXXX`; then
   echo "\$L2H_TMP = '$tmp_dir';" > l2h_tmp_dir.init
   echo "1;" >> l2h_tmp_dir.init
 else
diff -uNr texi2html-5.0/test/many_input_files/tex_t4ht.sh texi2html-5.0.fink/test/many_input_files/tex_t4ht.sh
--- texi2html-5.0/test/many_input_files/tex_t4ht.sh     2009-09-15 14:22:02.000000000 -0400
+++ texi2html-5.0.fink/test/many_input_files/tex_t4ht.sh        2012-10-02 11:04:44.000000000 -0400
@@ -18,7 +18,7 @@
 echo "$basename" > $logfile
 : > $stdout_file
 
-if tmp_dir=`mktemp -p /tmp -d l2h_t2h_XXXXXXXX`; then
+if tmp_dir=`mktemp -d l2h_t2h_XXXXXXXX`; then
   echo "\$L2H_TMP = '$tmp_dir';" > l2h_tmp_dir.init
   echo "1;" >> l2h_tmp_dir.init
 else
diff -uNr texi2html-5.0/test/run_test.sh texi2html-5.0.fink/test/run_test.sh
--- texi2html-5.0/test/run_test.sh      2010-02-21 13:27:16.000000000 -0500
+++ texi2html-5.0.fink/test/run_test.sh 2012-10-02 11:04:44.000000000 -0400
@@ -108,7 +108,7 @@
 [ -d "$diffs_dir" ] || mkdir "$diffs_dir"
 [ -d "$out_dir" ] || mkdir "$out_dir"
 
-if tmp_dir=`mktemp -p /tmp -d l2h_t2h_XXXXXXXX`; then
+if tmp_dir=`mktemp -d l2h_t2h_XXXXXXXX`; then
   echo "\$L2H_TMP = '$tmp_dir';" > l2h_tmp_dir.init
   echo "1;" >> l2h_tmp_dir.init
 else
@@ -182,21 +182,21 @@
       $out_dir/$dir/*_tex4ht_tex.html
   fi
   if [ $ret = 0 ]; then
-    sed -i -e 's/^texexpand.*/texexpand /' "$out_dir/$dir/$basename.2"
-    sed -i '/is no longer supported at.*line/d' "$out_dir/$dir/$basename.2"
+    sed -i '' -e 's/^texexpand.*/texexpand /' "$out_dir/$dir/$basename.2"
+    sed -i '' '/is no longer supported at.*line/d' "$out_dir/$dir/$basename.2"
     if [ "$use_latex2html" = 'yes' ]; then
-      sed -i -e 's/CONTENT="LaTeX2HTML.*/CONTENT="LaTeX2HTML">/' -e \
+      sed -i '' -e 's/CONTENT="LaTeX2HTML.*/CONTENT="LaTeX2HTML">/' -e \
        's/with LaTeX2HTML.*/with LaTeX2HTML/' "$out_dir/$dir/"*"_l2h.html"
       #<C2><A0>"*"_images.pl" files are not guaranteed to be present
       for file in "${outdir}$dir/"*"_images.pl" "${outdir}$dir/"*"_labels.pl"; do
        if [ -f "$file" ]; then
-        sed -i -e 's/^# LaTeX2HTML.*/# LaTeX2HTML/' "$file"
+        sed -i '' -e 's/^# LaTeX2HTML.*/# LaTeX2HTML/' "$file"
        fi
       done
       for file in "${outdir}$dir/"*.htm* "${outdir}$dir/"*-l2h_cache.pm "${outdir}$dir/"*_l2h_images.pl; do
        if [ -f "$file" ]; then
        # different rounding on different computers !
-        sed -i -e 's/WIDTH="\([0-9]*\)\([0-9]\)"/WIDTH="100"/' -e 's/HEIGHT="\([0-9]*\)\([0-9]\)"/HEIGHT="\10"/' "$file"
+        sed -i '' -e 's/WIDTH="\([0-9]*\)\([0-9]\)"/WIDTH="100"/' -e 's/HEIGHT="\([0-9]*\)\([0-9]\)"/HEIGHT="\10"/' "$file"
        fi
       done
       rm -f "$out_dir/$dir/"*".aux"  "$out_dir/$dir/"*"_images.out"
diff -uNr texi2html-5.0/test/run_test_all.sh texi2html-5.0.fink/test/run_test_all.sh
--- texi2html-5.0/test/run_test_all.sh  2010-02-21 13:27:07.000000000 -0500
+++ texi2html-5.0.fink/test/run_test_all.sh     2012-10-02 11:04:44.000000000 -0400
@@ -134,7 +134,7 @@
   [ -d "${outdir}" ] || mkdir "${outdir}"
 done
 
-if tmp_dir=`mktemp -p /tmp -d l2h_t2h_XXXXXXXX`; then
+if tmp_dir=`mktemp -d l2h_t2h_XXXXXXXX`; then
   echo "\$L2H_TMP = '$tmp_dir';" > l2h_tmp_dir.init
   echo "1;" >> l2h_tmp_dir.init
 else

, still fails parts of 'make check' against FSF sed 4.2.1. The failures appear as repeated instances of...

+Use of uninitialized value in lc at ./../../texi2html.pl line 2592.

in test/many_input_files/diffs/indices.diff and  test/many_input_files/diffs/tex_t4ht.diff. This appears to be due to the use of DOCUMENT_ENCODING which is no longer initialized in texi2html.init as in earlier texi2html releases. How should this be fixed?