Patch derived from discussion at https://savannah.nongnu.org/bugs/?37503

--- texi2html-5.0/texi2html.pl	2010-06-30 17:01:27.000000000 -0500
+++ texi2html-5.0/texi2html.pl	2014-07-09 01:17:57.062990582 -0500
@@ -2589,7 +2589,12 @@
     my $state = shift;
 
     # FIXME this should be done only once, for @documentencoding
-    my $encoding = lc(Texi2HTML::Config::get_conf('DOCUMENT_ENCODING'));
+    my $encoding;
+    my $input_encoding = Texi2HTML::Config::get_conf('documentencoding');
+    if (defined($input_encoding))
+    {
+      $encoding = lc($input_encoding);
+    }
     if (defined($encoding) and $encoding ne '' and exists($Texi2HTML::Config::t2h_encoding_aliases{$encoding}))
     {
        $encoding = $Texi2HTML::Config::t2h_encoding_aliases{$encoding};

Fix failures in test/encodings.

--- texi2html-5.0/texi2html.pl	2014-07-09 01:22:06.000000000 -0500
+++ texi2html-5.0/texi2html.pl	2014-07-10 23:23:47.182097602 -0500
@@ -53,6 +53,7 @@
 # for translations
 #use encoding 'utf8';
 #use utf8;
+binmode STDERR, ':encoding(utf8)';
 
 #
 # According to
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<input type='hidden' name='id' value='8a442e5db2989df6283b323fc8176df75972bab2'/><select name='qt'>
<option value='grep'>log msg</option>
<option value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
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<tr><td><span title='2018-03-25 05:01:55 -0400'>2018-03-25</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=8a442e5db2989df6283b323fc8176df75972bab2'>gnu: asciidoc: Restore custom 'bootstrap' phase.</a><span class='msg-avail'>...</span></td><td>Mark H Weaver</td></tr>
<tr><td><span title='2018-03-11 22:04:40 +0100'>2018-03-11</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=189be331acfda1c242a9c85fca8d2a0356742f48'>build-system/gnu: Add 'bootstrap' phase.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2018-02-09 01:46:34 -0500'>2018-02-09</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=efe2a2833c6d306d0c60127fdfebaff6dc415b4c'>Merge branch 'master' into core-updates</a></td><td>Mark H Weaver</td></tr>
<tr><td><span title='2018-02-06 20:02:12 +0100'>2018-02-06</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=ccfe4aa1c09b5205a1d17070eb4f9f6da59650bc'>gnu: asciidoc: Update to 8.6.10.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2017-11-11 17:28:51 +0200'>2017-11-11</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=738d0cd665ef89a77af0b1568aea68d29bc749d6'>gnu: doxygen: Build with flex@2.6.1.</a><span class='msg-avail'>...</span></td><td>Efraim Flashner</td></tr>
<tr><td><span title='2017-08-29 20:13:24 -0400'>2017-08-29</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=3c8ba11a97d3f3b671b8919da8c41f0b0e2ccaf3'>Update e-mail for Kei Kebreau.</a><span class='msg-avail'>...</span></td><td>Kei Kebreau</td></tr>
<tr><td><span title='2017-06-20 18:10:35 +0530'>2017-06-20</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=148585c240f848ad08f6541ede7db3fca3411007'>gnu: Move contents of zip module into compression module.</a><span class='msg-avail'>...</span></td><td>Arun Isaac</td></tr>
<tr><td><span title='2017-03-19 18:52:12 -0400'>2017-03-19</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=f67337e23ec16b1e05fcdcc7953f68f13ed6770a'>Merge branch 'master' into core-updates</a></td><td>Mark H Weaver</td></tr>
<tr><td><span title='2017-03-16 21:35:50 -0400'>2017-03-16</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=3078821d1380c26c738be6b5d430c595327d401f'>gnu: asciidoc: Use local docbook-xml package.</a><span class='msg-avail'>...</span></td><td>Kei Kebreau</td></tr>
<tr><td><span title='2017-03-15 17:52:26 +0100'>2017-03-15</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=4b7e5c1131430f10e6211879836cf17447ef5bbc'>Merge branch 'master' into core-updates</a></td><td>Marius Bakke</td></tr>
<tr><td><span title='2017-03-14 15:57:54 -0400'>2017-03-14</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=9099a45792306fade2d9ca55138e49ef4f01f1ea'>gnu: asciidoc: Add XML and XSLT support.</a><span class='msg-avail'>...</span></td><td>Kei Kebreau</td></tr>
<tr><td><span title='2017-02-28 02:09:51 -0500'>2017-02-28</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=f3a24b46c82f6a8e9f2638cbfe01f70abc4de04f'>gnu: doxygen: Update to 1.8.13.</a><span class='msg-avail'>...</span></td><td>Leo Famulari</td></tr>
<tr><td><span title='2017-01-17 03:55:31 -0500'>2017-01-17</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=603308ee601b9ca96e90822b61b4e150106db425'>gnu: doxygen: Use sh from the store.</a><span class='msg-avail'>...</span></td><td>Thomas Danckaert</td></tr>
<tr><td><span title='2016-09-28 17:54:50 +0300'>2016-09-28</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=b94a6ca074f00b3f769933d074853d3c3ca50d00'>gnu: Add and use gettext-minimal.</a><span class='msg-avail'>...</span></td><td>Alex Kost</td></tr>
<tr><td><span title='2016-08-21 17:42:57 -0400'>2016-08-21</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=dd10ba6356df83cc7e44fc6cadaa2c8c9749bd69'>gnu: asciidoc: Use local docbook-xsl package.</a><span class='msg-avail'>...</span></td><td>Tomáš Čech</td></tr>
<tr><td><span title='2016-07-21 18:09:40 -0400'>2016-07-21</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=de67e922885baf68a746a0484ca0b45e45b0964b'>gnu: Update URLs for sourceforge.net.</a><span class='msg-avail'>...</span></td><td>Leo Famulari</td></tr>
<tr><td><span title='2016-07-04 21:32:31 +0200'>2016-07-04</span></td><td><a href='/guix/commit/gnu/packages/documentation.scm?id=fa8af53e99afd932b2e534a428ea6ac62581c89d'>gnu: Add scrollkeeper.</a><span class='msg-avail'>...</span></td><td>Roel Janssen</td></tr>