build/linux: Use custom App ID on Nightly flatpak

This avoids DEs mixing icons from stable/beta with nightly.

.gitlab-ci.yml

@@ -833,7 +833,7 @@ dist-flatpak-weekly:
   artifacts:
     expose_as: 'Linux flatpak'
     paths:
-      - org.gimp.GIMP.flatpak
+      - org.gimp.GIMP.Nightly.flatpak
     expire_in: 8 days
 
 dist-installer-weekly:

build/linux/flatpak/3_dist-gimp-flatpak.sh

@@ -11,8 +11,8 @@ fi
 
 # Generate a Flatpak "bundle" to be tested with GNOME runtime installed
 # (it is NOT a real/full bundle, deps from GNOME runtime are not bundled)
-echo -e "\e[0Ksection_start:`date +%s`:flat_making[collapsed=true]\r\e[0KPackaging repo as org.gimp.GIMP.flatpak"
-flatpak build-bundle repo org.gimp.GIMP.flatpak --runtime-repo=https://nightly.gnome.org/gnome-nightly.flatpakrepo org.gimp.GIMP ${BRANCH}
+echo -e "\e[0Ksection_start:`date +%s`:flat_making[collapsed=true]\r\e[0KPackaging repo as org.gimp.GIMP.Nightly.flatpak"
+flatpak build-bundle repo org.gimp.GIMP.Nightly.flatpak --runtime-repo=https://nightly.gnome.org/gnome-nightly.flatpakrepo org.gimp.GIMP.Nightly ${BRANCH}
 echo -e "\e[0Ksection_end:`date +%s`:flat_making\r\e[0K"
 
 

build/linux/flatpak/org.gimp.GIMP-nightly.json

@@ -1,5 +1,5 @@
 {
-    "app-id": "org.gimp.GIMP",
+    "app-id": "org.gimp.GIMP.Nightly",
     "branch": "master",
     "runtime": "org.gnome.Platform",
     "runtime-version": "master",
@@ -15,6 +15,7 @@
         "cxxflags": "-fdiagnostics-color=always"
     },
     "separate-locales": false,
+    "rename-appdata-file": "org.gimp.GIMP.appdata.xml",
     "rename-desktop-file": "gimp.desktop",
     "rename-icon": "gimp",
     "copy-icon": true,