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;
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<div class='path'>path: <a href='/guix/log/?id=65ddb638fa105a47e0c0a1f5062dbecf8ab3af49'>root</a>/<a href='/guix/log/tests?id=65ddb638fa105a47e0c0a1f5062dbecf8ab3af49'>tests</a>/<a href='/guix/log/tests/discovery.scm?id=65ddb638fa105a47e0c0a1f5062dbecf8ab3af49'>discovery.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/discovery.scm?id=65ddb638fa105a47e0c0a1f5062dbecf8ab3af49&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2017-07-03 23:51:23 +0200'>2017-07-03</span></td><td><a href='/guix/commit/tests/discovery.scm?id=960c6ce96d746cf19829ad26e092ec5dad2a5c62'>discovery: Recurse into directories pointed to by a symlink.</a><span class='msg-avail'>...<span class='msg-tooltip'>Reported by Christopher Baines &lt;mail@cbaines.net&gt;
and Alex Kost &lt;alezost@gmail.com&gt;
at &lt;https://lists.gnu.org/archive/html/guix-devel/2017-06/msg00290.html&gt;.

* guix/discovery.scm (scheme-files): When ENTRY is a symlink that
doesn't end in '.scm', call 'stat' and recurse if it points to a
directory.
* tests/discovery.scm ("scheme-modules recurses in symlinks to
directories"): New test.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-06-18 00:14:07 +0200'>2017-06-18</span></td><td><a href='/guix/commit/tests/discovery.scm?id=d46c4423f46278bd2f96770ceb0667431414349e'>discovery: 'scheme-files' returns '() for a non-accessible directory.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes a regression introduced in
d27cc3bfaafe6b5b0831e88afb1c46311d382a0b.

Reported by Ricardo Wurmus &lt;rekado@elephly.net&gt;.

* guix/discovery.scm (scheme-files): Catch 'scandir*' system errors.
Return '() and optionally raise a warning upon 'system-error'.
* tests/discovery.scm ("scheme-modules, non-existent directory"): New
test.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2017-05-03 23:50:15 +0200'>2017-05-03</span></td><td><a href='/guix/commit/tests/discovery.scm?id=cd903ef7871170d3c4eced45418459d293ef48a7'>Add (guix discovery).</a><span class='msg-avail'>...<span class='msg-tooltip'>* guix/discovery.scm, tests/discovery.scm: New files.
* gnu/packages.scm (scheme-files, file-name-&gt;module-name)
(scheme-modules, all-package-modules): Remove.
(fold-packages): Rewrite in terms of 'fold-module-public-variables'.
* gnu/tests.scm: Use (guix discovery).
* Makefile.am (MODULES): Add guix/discovery.scm.
(SCM_TESTS): Add tests/discovery.scm.
</span></span></td><td>Ludovic Courtès</td></tr>