github actions: introduce workflow_dispatch trigger for rebuilding packages

.github/workflows/packages.yml

@@ -9,6 +9,11 @@ on:
   pull_request:
     paths:
     - 'packages/**'
+  workflow_dispatch:
+    inputs:
+      packages:
+        description: "A space-separated names of packages selected for rebuilding"
+        required: true
 
 jobs:
   build:
@@ -27,6 +32,7 @@ jobs:
         fetch-depth: 1000
     - name: Build
       run: |
+        if [ "${{ github.event_name }}" != "workflow_dispatch" ]; then
           BASE_COMMIT=$(jq --raw-output .pull_request.base.sha "$GITHUB_EVENT_PATH")
           OLD_COMMIT=$(jq --raw-output .commits[0].id "$GITHUB_EVENT_PATH")
           HEAD_COMMIT=$(jq --raw-output .commits[-1].id "$GITHUB_EVENT_PATH")
@@ -46,8 +52,10 @@ jobs:
             echo "Processing pull request #$(jq --raw-output .pull_request.number "$GITHUB_EVENT_PATH"): ${BASE_COMMIT}..HEAD"
             CHANGED_FILES=$(git diff-tree --no-commit-id --name-only -r "${BASE_COMMIT}" "HEAD")
           fi
+        fi
         mkdir -p ./artifacts ./debs
         touch ./debs/.placeholder
+        if [ "${{ github.event_name }}" != "workflow_dispatch" ]; then
           # Process tag '%ci:no-build' that may be added as line to commit message.
           # Forces CI to cancel current build with status 'passed'.
           if grep -qiP '^\s*%ci:no-build\s*$' <(git log --format="%B" -n 1 "HEAD"); then
@@ -93,6 +101,11 @@ jobs:
               fi
             fi
           done<<<${CHANGED_FILES}
+        else
+          for i in ${{ github.event.inputs.packages }}; do
+            echo "$i" >> ./built_packages.txt
+          done
+        fi
 
         # Fix so that lists do not contain duplicates
         if [ -f ./built_packages.txt ]; then