Flatpak writes files for installed applications with the full Flatpak (store) path. This patch makes it write just "flatpak", using Flatpak from PATH. This is similar to the NixOS [0] patch, updated for Flatpak 1.12.1

[0] https://github.com/NixOS/nixpkgs/blob/bf4167861d0f864b0fc457778d54feb4a2675ea2/pkgs/development/libraries/flatpak/use-flatpak-from-path.patch

diff --git a/common/flatpak-dir.c b/common/flatpak-dir.c
index 80ff5e5f..0c111c31 100644
--- a/common/flatpak-dir.c
+++ b/common/flatpak-dir.c
@@ -7134,8 +7134,7 @@ export_desktop_file (const char         *app,
         flatpak = FLATPAK_BINDIR "/flatpak";

       g_string_append_printf (new_exec,
-                              "%s run --branch=%s --arch=%s",
-                              flatpak,
+                              "flatpak run --branch=%s --arch=%s",
                               escaped_branch,
                               escaped_arch);

@@ -8467,8 +8466,8 @@ flatpak_dir_deploy (FlatpakDir          *self,
       if ((flatpak = g_getenv ("FLATPAK_BINARY")) == NULL)
         flatpak = FLATPAK_BINDIR "/flatpak";

-      bin_data = g_strdup_printf ("#!/bin/sh\nexec %s run --branch=%s --arch=%s %s \"$@\"\n",
-                                  flatpak, escaped_branch, escaped_arch, escaped_app);
+      bin_data = g_strdup_printf ("#!/bin/sh\nexec flatpak run --branch=%s --arch=%s %s \"$@\"\n",
+                                  escaped_branch, escaped_arch, escaped_app);
       if (!g_file_replace_contents (wrapper, bin_data, strlen (bin_data), NULL, FALSE,
                                     G_FILE_CREATE_REPLACE_DESTINATION, NULL, cancellable, error))
         return FALSE;
e='hidden' name='id' value='d3281df55141583f9d08d713ad30718acd97c1c4'/><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=''/>
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</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=d3281df55141583f9d08d713ad30718acd97c1c4'>root</a>/<a href='/guix/log/etc?id=d3281df55141583f9d08d713ad30718acd97c1c4'>etc</a>/<a href='/guix/log/etc/time-travel-manifest.scm?id=d3281df55141583f9d08d713ad30718acd97c1c4'>time-travel-manifest.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/etc/time-travel-manifest.scm?id=d3281df55141583f9d08d713ad30718acd97c1c4&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-09-09 19:36:05 +0200'>2023-09-09</span></td><td><a href='/guix/commit/etc/time-travel-manifest.scm?id=a4c35c607cfd7d6b0bad90cfcc46188d489e1754'>time-travel-manifest: Comment out versions older than 1.3.0 for now.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/time-travel-manifest.scm (%release-commits): Comment out revisions
older than 1.3.0.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-09-09 19:33:31 +0200'>2023-09-09</span></td><td><a href='/guix/commit/etc/time-travel-manifest.scm?id=d4bd5bc799e2face0b30bdb3a6ec3c347c0d1e22'>time-travel-manifest: Add 1.4.0.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/time-travel-manifest.scm (%release-commits): Add 1.4.0.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-08-17 15:42:56 +0200'>2022-08-17</span></td><td><a href='/guix/commit/etc/time-travel-manifest.scm?id=845c841e21379e64a4215ee6d3d60da343e7fb93'>time-travel-manifest: Use a separate cache per system.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/time-travel-manifest.scm (&lt;guix-instance-compiler&gt;): Use a separate
cache per system so that parallel system evaluations do no step on each
other's toes.
</span></span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2022-07-10 23:57:14 +0200'>2022-07-10</span></td><td><a href='/guix/commit/etc/time-travel-manifest.scm?id=5d0437ea8ce0147b47b9df866fa2413b48f71a1a'>time-travel-manifest: Use a separate Git checkout cache.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/time-travel-manifest.scm (guix-instance-compiler): Parameterize
%REPOSITORY-CACHE-DIRECTORY.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-07-08 23:58:11 +0200'>2022-07-08</span></td><td><a href='/guix/commit/etc/time-travel-manifest.scm?id=e80f0cda96181d90604c44f69094f2499036b3f6'>etc: Add 'time-travel-manifest.scm'.</a><span class='msg-avail'>...<span class='msg-tooltip'>This manifest makes it easy to test travels from the current revision
back to the revision of a past Guix release.

Suggested by zimoun &lt;zimon.toutoune@gmail.com&gt;.

* etc/time-travel-manifest.scm: New file.
* Makefile.am (EXTRA_DIST): Add it.
</span></span></td><td>Ludovic Courtès</td></tr>