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.
'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=720a4adc91c632e097d9e064ce8e95617cf76fb0'>root</a>/<a href='/guix/log/tests?id=720a4adc91c632e097d9e064ce8e95617cf76fb0'>tests</a>/<a href='/guix/log/tests/processes.scm?id=720a4adc91c632e097d9e064ce8e95617cf76fb0'>processes.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/tests/processes.scm?id=720a4adc91c632e097d9e064ce8e95617cf76fb0&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2019-12-10 10:49:42 +0100'>2019-12-10</span></td><td><a href='/guix/commit/tests/processes.scm?id=0b5ad0e756a34d5e3ed1f37c3d4083a330fa33f5'>tests: processes: Skip tests if running with binfmt.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/processes.scm (binfmt-misc?): New procedure,
(test-assert*): new procedure that skips the test if binfmt-misc? returns
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2018-10-29 00:13:38 +0100'>2018-10-29</span></td><td><a href='/guix/commit/tests/processes.scm?id=63eb2b899be7ac857454442e09d0ebd23fe4f871'>Add 'guix processes'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/scripts/processes.scm, tests/processes.scm: New files.
* Makefile.am (MODULES): Add the former.
(SCM_TESTS): Add the latter.
* po/guix/POTFILES.in: Add guix/scripts/processes.scm.
* doc/guix.texi (Invoking guix processes): New node.
(Invoking guix-daemon): Reference it.
</span></span></td><td>Ludovic Courtès</td></tr>