chore(ci): update vscode cache logic

Author: Akash Satheesan

.github/workflows/ci.yaml

@@ -83,7 +83,9 @@ jobs:
       # use this to avoid rebuilding it if nothing changed
       - name: Get latest lib/vscode rev
         id: vscode-rev
-        run: echo "::set-output name=rev::$(git log -1 --format='%H' lib/vscode)"
+        run: |
+          ./ci/steps/git-deepen.sh
+          echo "::set-output name=rev::$(git log -1 --format='%H' ./lib/vscode)"
 
       - name: Attempt to fetch vscode build from cache
         id: cache-vscode
@@ -165,7 +167,7 @@ jobs:
   test-e2e:
     name: End-to-end tests
     needs: linux-amd64
-    runs-on: ubuntu-16.04
+    runs-on: ubuntu-latest
     env:
       PASSWORD: e45432jklfdsab
       CODE_SERVER_ADDRESS: http://localhost:8080

ci/steps/git-deepen.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# progressively deepen a clone until we reach a non-grafted commit.
+# used for getting the last lib/vscode commit for caching builds
+# without pulling the whole git history for performance reasons.
+main() {
+  cd "$(dirname "$0")/../.."
+
+  while git log -1 --oneline --decorate lib/vscode | grep grafted; do
+    git fetch --deepen=10
+  done
+}
+
+main "$@"