This test fails because it expects a MIME type "Content-Type: image/gif"
whereas that provided by libmagic is "Content-Type: image/gif; charset=binary"
Presumably the test was written against a different version.
--- aegis-4.24/test/02/t0228a-matt.sh	2008-03-14 07:19:27.000000000 +0100
+++ aegis-4.24/test/02/t0228a-matt.sh	2014-01-27 09:43:44.000000000 +0100
@@ -147,7 +147,8 @@
 SCRIPT_NAME=/cgi-bin/aeget \
 PATH_INFO=icon/rss.gif \
 QUERY_STRING= \
-$bin/aeget > rss.served.gif 2>&1
+$bin/aeget \
+| sed -e 's%^Content-Type: image/gif; charset=binary%Content-Type: image/gif%' > rss.served.gif 2>&1
 if test $? -ne 0 ; then fail; fi
 
 # Compare the expected and the actual received file.
'/><select name='h' onchange='this.form.submit();'>
<option value='koszko' selected='selected'>koszko</option>
<option value='koszko-scripts'>koszko-scripts</option>
</select> <input type='submit' value='switch'/></form></td></tr>
<tr><td class='sub'>Wojtek's customized Guix</td><td class='sub right'></td></tr></table>
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<div class='path'>path: <a href='/guix/log/?id=cb3290e72023b94f0ce7d59745f830c4e8e9ad78'>root</a>/<a href='/guix/log/gnu?id=cb3290e72023b94f0ce7d59745f830c4e8e9ad78'>gnu</a>/<a href='/guix/log/gnu/bootloader?id=cb3290e72023b94f0ce7d59745f830c4e8e9ad78'>bootloader</a>/<a href='/guix/log/gnu/bootloader/extlinux.scm?id=cb3290e72023b94f0ce7d59745f830c4e8e9ad78'>extlinux.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/bootloader/extlinux.scm?id=cb3290e72023b94f0ce7d59745f830c4e8e9ad78&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-08-30 08:50:44 +0200'>2022-08-30</span></td><td><a href='/guix/commit/gnu/bootloader/extlinux.scm?id=f126f23b132148192b2c9a89032a5831af0b3c52'>bootloader: Add device-tree-support? option.</a><span class='msg-avail'>...<span class='msg-tooltip'>In some specific cases where the device tree file is already loaded in RAM, it
can be preferable that the bootloader does not try to use a device tree from
the Linux kernel tree.

* gnu/bootloader.scm (&lt;bootloader-configuration&gt;)[device-tree-support?]: New field.
* gnu/bootloader/extlinux.scm (extlinux-configuration-file): Add FDTDIR line
based on &lt;device-tree-support?&gt; field of &lt;bootloader-configuration&gt;.
* doc/guix.texi (Bootloader Configuration)[device-tree-support?]: Add
documentation for the new field.
</span></span></td><td>Reza Alizadeh Majd</td></tr>