Most Guix system setup with desktop evironment will install GDK_PIXBUF_MODULE_FILE
environment variable in the system profile, and it'll be leaked into the sandbox
environment of flatpak, so the applications in sandbox may fail to find correct
GdkPixbuf loaders.

This patch unset the GDK_PIXBUF_MODULE_FILE environment variable before running
the sandboxed applications, prevents it to load GdkPixbuf loaders from the path
of host system.

--- a/common/flatpak-run.c
+++ b/common/flatpak-run.c
@@ -1900,6 +1900,7 @@ static const ExportData default_exports[] = {
   {"XKB_CONFIG_ROOT", NULL},
   {"GIO_EXTRA_MODULES", NULL},
   {"GDK_BACKEND", NULL},
+  {"GDK_PIXBUF_MODULE_FILE", NULL},
 };
 
 static const ExportData no_ld_so_cache_exports[] = {

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<div class='path'>path: <a href='/guix/log/?id=aceb4e49d1d802cf428d8873dcb9dc3196996066'>root</a>/<a href='/guix/log/tests?id=aceb4e49d1d802cf428d8873dcb9dc3196996066'>tests</a>/<a href='/guix/log/tests/gremlin.scm?id=aceb4e49d1d802cf428d8873dcb9dc3196996066'>gremlin.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/gremlin.scm?id=aceb4e49d1d802cf428d8873dcb9dc3196996066&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2022-01-16 20:21:27 -0800'>2022-01-16</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=24c3485bb3ffc05e687ef6513ac287b8d3048bab'>tests: Fix file-needed/recursive on aarch64-linux.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes: &lt;https://issues.guix.gnu.org/52943&gt;.

* tests/gremlin.scm (file-needed/recursive)[ground-truth]: On aarch64-linux,
remove the dynamic linker from this list.
</span></span></td><td>Pierre Langlois</td></tr>
<tr><td><span title='2022-01-14 22:39:24 +0100'>2022-01-14</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=e7ad192de008a6a21638def6eb973b9cc0c91116'>gremlin: Adjust tests for i686 and beyond.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://issues.guix.gnu.org/52752&gt;.
Reported by Denis 'GNUtoo' Carikli &lt;GNUtoo@cyberdimension.org&gt;.

* tests/gremlin.scm ("file-needed/recursive"): Augment the list of vDSO
names.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-01-08 15:51:22 -0800'>2022-01-08</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=6a2050b1e1c7f09ef9b6af43044b7c0e4786d39d'>tests: Fix file-needed/recursive on powerpc64le-linux.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes: &lt;https://issues.guix.gnu.org/52940&gt;.

* tests/gremlin.scm (file-needed/recursive): Consider two entries to be
equivalent not when they are the same string, but rather when they refer to
the same file.
[ground-truth]: In addition to strings that begin with "linux-vdso.so", remove
strings that begin with "linux-vdso64.so".
</span></span></td><td>Chris Marusich</td></tr>
<tr><td><span title='2021-06-23 20:30:22 -0700'>2021-06-23</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=e4b5a23841bc6a92e2e21dd8b1038addee55eb02'>tests: gremlin: Skip file-needed/recursive if DT_NEEDED is empty.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/gremlin.scm (file-needed/recursive): Skip the test when (file-runpath
%guile-executable) evaluates to the empty list.  This causes the test to be
correctly skipped in the case where Guix has been built using a foreign
distro's toolchain and libraries.
</span></span></td><td>Chris Marusich</td></tr>
<tr><td><span title='2021-04-22 14:04:27 +0200'>2021-04-22</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=1010171280cb34c8dc361644b66fdd1a041d297a'>gremlin: 'elf-dynamic-info' returns a file name rathern than a dynamic entry.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/gremlin.scm (elf-dynamic-info): Return the dynamic entry
value, not the dynamic entry.
* tests/gremlin.scm ("elf-dynamic-info-soname"): New test.

Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Dion Mendel</td></tr>
<tr><td><span title='2020-12-01 21:30:28 +0100'>2020-12-01</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=53fd256e5ba43e516fb9d6eaf085b88fe8bd12b6'>gremlin: Add 'file-needed/recursive'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/gremlin.scm (file-needed/recursive): New procedure.
* tests/gremlin.scm ("file-needed/recursive"): New test.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-09-19 17:28:46 +0200'>2020-09-19</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=49a1203d67a90a6a7ce4e4537697a6da96ceb213'>gremlin: Add 'set-file-runpath', 'file-runpath', and 'file-needed'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/build/gremlin.scm (file-dynamic-info, file-runpath, file-needed):
New procedures.
(&amp;missing-runpath-error, &amp;runpath-too-long-error): New condition types.
(set-file-runpath): New procedure.
* tests/gremlin.scm ("set-file-runpath + file-runpath"): New test.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2019-05-18 12:10:15 +0200'>2019-05-18</span></td><td><a href='/guix/commit/tests/gremlin.scm?id=6b97415996583b15a97dad8254f610275353e913'>gremlin: Adjust tests for foreign distros.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;https://bugs.gnu.org/35775&gt;.

* tests/gremlin.scm ("elf-dynamic-info-needed, executable"): Expect only
libguile and libc among NEEDED.
("strip-runpath"): Pass '--enable-new-dtags' to get RUNPATH, not RPATH.
</span></span></td><td>Ting-Wei Lan</td></tr>