ci: delete CL build branches once workflow is complete

In ccbfbd2 we introduced the concept of build branches that are used
for CL CI workflows. However we stopped short of deleting those build
branches to ensure that the workflow behaved as intended on master.

There have been two subsequent master builds, a pass and a fail, that
verify this remove step is not running for a master build:

https://github.com/cuelang/cue/actions/runs/488463317 (fail)
https://github.com/cuelang/cue/actions/runs/488888616 (pass)

Hence it is now safe to remove build branches at the end of a CL
workflow.

Change-Id: Iad673771470e50d2e568e2caf451fc21a41a573e
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/8226
Reviewed-by: CUE cueckoo <cueckoo@gmail.com>
Reviewed-by: Paul Jolly <paul@myitcv.org.uk>

.github/workflows/test.yml

@@ -88,4 +88,11 @@ jobs:
       run:
         shell: bash
     steps:
-    - run: echo git push origin :${GITHUB_REF#refs/heads/}
+    - run: |-
+        mkdir tmpgit
+        cd tmpgit
+        git init
+        git config user.name cueckoo
+        git config user.email cueckoo@gmail.com
+        git config http.https://github.com/.extraheader "AUTHORIZATION: basic $(echo -n cueckoo:${{ secrets.CUECKOO_GITHUB_PAT }} | base64)"
+        git push https://github.com/cuelang/cue :${GITHUB_REF#refs/heads/}

internal/ci/workflows.cue

@@ -70,7 +70,10 @@ test: _#bashWorkflow & {
 			needs:     "test"
 			steps: [
 				_#step & {
-					run: "echo git push origin :${GITHUB_REF#\(_#branchRefPrefix)}"
+					run: """
+						\(_#tempCueckooGitDir)
+						git push https://github.com/cuelang/cue :${GITHUB_REF#\(_#branchRefPrefix)}
+						"""
 				},
 			]
 		}
@@ -155,13 +158,8 @@ test_dispatch: _#bashWorkflow & {
 				},
 				_#step & {
 					name: "Checkout ref"
-					run: """
-						mkdir tmpgit
-						cd tmpgit
-						git init
-						git config user.name cueckoo
-						git config user.email cueckoo@gmail.com
-						git config http.https://github.com/.extraheader "AUTHORIZATION: basic $(echo -n cueckoo:${{ secrets.CUECKOO_GITHUB_PAT }} | base64)"
+					run:  """
+						\(_#tempCueckooGitDir)
 						git fetch https://cue-review.googlesource.com/cue ${{ github.event.client_payload.ref }}
 						git checkout -b ci/${{ github.event.client_payload.changeID }}/${{ github.event.client_payload.commit }} FETCH_HEAD
 						git push https://github.com/cuelang/cue ci/${{ github.event.client_payload.changeID }}/${{ github.event.client_payload.commit }}
@@ -339,3 +337,12 @@ _#writeCookiesFile: _#step & {
 }
 
 _#branchRefPrefix: "refs/heads/"
+
+_#tempCueckooGitDir: """
+	mkdir tmpgit
+	cd tmpgit
+	git init
+	git config user.name cueckoo
+	git config user.email cueckoo@gmail.com
+	git config http.https://github.com/.extraheader "AUTHORIZATION: basic $(echo -n cueckoo:${{ secrets.CUECKOO_GITHUB_PAT }} | base64)"
+	"""