Make some of the changes needed to the 'makeicecat' script, to allow it to run
in a snippet without network access.  After this patch is applied, some
additional changes will be made using 'substitute*'.

diff --git a/makeicecat b/makeicecat
index bf2b7a6..bc3b19b 100755
--- a/makeicecat
+++ b/makeicecat
@@ -56,7 +56,7 @@ readonly SOURCEDIR=icecat-${FFVERSION}
 # debug/shell options
 readonly DEVEL=0
 set -euo pipefail
-(( DEVEL )) && set -x
+set -x
 
 
 ###############################################################################
@@ -455,7 +455,7 @@ configure_search()
 
 
     # Process various JSON pre-configuration dumps.
-    python3 ../../tools/process-json-files.py . browser/components/extensions/schemas/
+    python3 "${DATADIR}"/../tools/process-json-files.py . browser/components/extensions/schemas/
 }
 
 configure_mobile()
@@ -837,12 +837,12 @@ finalize_sourceball()
 # entry point
 ###############################################################################
 
-validate_env || exit 1
-prepare_env
-fetch_source
-verify_sources
-extract_sources
-fetch_l10n
+# validate_env || exit 1
+# prepare_env
+# fetch_source
+# verify_sources
+# extract_sources
+# fetch_l10n
 apply_patches
 configure
 configure_search
@@ -854,4 +854,4 @@ prepare_macos_packaging
 configure_extensions
 configure_onboarding
 apply_bugfixes
-finalize_sourceball
+# finalize_sourceball
a81d3973851ee3a2'>commit</a><a href='/guix/diff/etc/system-tests.scm?id=3fef44ed6c21e5bbc0da60d8a81d3973851ee3a2'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/etc/system-tests.scm'>
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<div class='path'>path: <a href='/guix/log/?id=3fef44ed6c21e5bbc0da60d8a81d3973851ee3a2'>root</a>/<a href='/guix/log/etc?id=3fef44ed6c21e5bbc0da60d8a81d3973851ee3a2'>etc</a>/<a href='/guix/log/etc/system-tests.scm?id=3fef44ed6c21e5bbc0da60d8a81d3973851ee3a2'>system-tests.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/system-tests.scm?id=3fef44ed6c21e5bbc0da60d8a81d3973851ee3a2&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-03-23 00:06:58 +0100'>2020-03-23</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=8b18f5cb309f670b08ad35df6425f4e9e19d8a82'>tests: Use the same source as ci.guix.gnu.org.</a><span class='msg-avail'>...<span class='msg-tooltip'>* etc/system-tests.scm (system-test-manifest): In 'local-file' call, use
a name that is a function of COMMIT to match what Cuirass does.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2020-03-05 16:33:38 +0100'>2020-03-05</span></td><td><a href='/guix/commit/etc/system-tests.scm?id=5ec4156bbcaec8337f78411204d59e59e706103b'>tests: Add a manifest for system tests.</a><span class='msg-avail'>...<span class='msg-tooltip'>The manifest can be passed to 'guix build -m', 'guix weather -m', and so
on.  It can also be passed to an installed 'guix' (without
./pre-inst-env), with the exception so far of installation tests.

* build-aux/run-system-tests.scm: Remove.  Move interesting bits move
to...
* etc/system-tests.scm: ... here.  New file.
* Makefile.am (EXTRA_DIST): Remove 'build-aux/run-system-tests.scm' and
add 'etc/system-tests.scm'.
(check-system): Rewrite to run 'guix build -m etc/system-tests.scm'.
</span></span></td><td>Ludovic Courtès</td></tr>