restructure to patch + shell scripts executed by a generic wrapper

Dockerfile

@@ -1,12 +1,14 @@
 ARG VERSION=latest
 FROM gitlab/gitlab-ee:$VERSION
 
+# re-set VERSION as its cleared after a FROM directive
 ARG VERSION
-COPY patches/${VERSION} /patches
-RUN set -e; for p in /patches/*; do patch -p0 < $p; done
 
+# copy static files
 COPY templates/arc.tar.gz /opt/gitlab/embedded/service/gitlab-rails/vendor/project_templates/
 COPY assets/dataplant-arc.png assets/house-solid.svg /opt/gitlab/embedded/service/gitlab-rails/public/assets/
 
-#COPY pages.projects.new.5b691961.chunk.js.gz /opt/gitlab/embedded/service/gitlab-rails/public/assets/webpack/
-#COPY pages.projects.new.5b691961.chunk.js.map.gz /opt/gitlab/embedded/service/gitlab-rails/public/assets/webpack/
+# copy and execute the patch scripts
+COPY scripts/${VERSION} /scripts
+RUN /scripts/patch.sh
+

scripts/15.10.1-ee.0/patch.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+set -ex
+
+for patch in /scripts/patches/*.patch; do
+	patch -p0 < "$patch"
+done
+
+for script in /scripts/patches/*.sh; do
+	"$script"
+done

scripts/15.10.1-ee.0/patches/add-arc-js.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+set -e
+
+set -- /opt/gitlab/embedded/service/gitlab-rails/public/assets/webpack/pages.projects.imports.new.*.chunk.js
+
+# exit if above's glob matches nothing or more than 1 file
+[ -e "$1" ] && [ "$#" = "1" ]
+
+# the mighty "patch"
+sed -Ei.bak \
+	's/sample:(\{text:Object\([^)]+\))/arc:\1("ProjectTemplates|ARC"),icon:".template-option .icon-gitlab_logo"},&/' \
+	"$1"
+
+# needs to be gzip'ed too
+gzip -kf "$1"
+
+# print diffs to see what was done
+diff -u "$1" "${1}.bak" || true