Fix test-as-submodule CI. (#784)

* Also update the GitHub PR template.

Author: olupton

.github/pull_request_template.md

@@ -28,6 +28,15 @@ nrnivmodl mod
  - Version: [e.g. master branch]
  - Backend: [e.g. CPU]
 
-**Use certain branches for the SimulationStack CI**
-
-CI_BRANCHES:NEURON_BRANCH=master,
+**Use certain branches in CI pipelines.**
+<!-- You can steer which versions of CoreNEURON dependencies will be used in
+     the various CI pipelines (GitLab, test-as-submodule) here. Expressions are
+     of the form PROJ_REF=VALUE, where PROJ is the relevant Spack package name,
+     transformed to upper case and with hyphens replaced with underscores.
+     REF may be BRANCH, COMMIT or TAG, with exceptions:
+      - SPACK_COMMIT and SPACK_TAG are invalid (hpc/gitlab-pipelines limitation)
+      - NEURON_COMMIT and NEURON_TAG are invalid (test-as-submodule limitation)
+     These values for NEURON, nmodl and Spack are the defaults and are given
+     for illustrative purposes; they can safely be removed.
+-->
+CI_BRANCHES:NEURON_BRANCH=master,NMODL_BRANCH=master,SPACK_BRANCH=develop

.github/workflows/test-as-submodule.yml

@@ -54,9 +54,9 @@ jobs:
         env:
           GITHUB_PR_BODY: ${{ github.event.pull_request.body }}
         run: |
-          nrn_branch=`echo "${GITHUB_PR_BODY}" | grep "^CI_BRANCHES" \
-                      | awk -v FS="NEURON_BRANCH=" '{print $2}'` \
-                      | awk -v FS="," '{print $1}'
+          nrn_branch=$(echo "${GITHUB_PR_BODY}" | grep "^CI_BRANCHES" \
+                      | awk -F '[:,]{1}NEURON_BRANCH=' '{print $2}' \
+                      | awk -F ',' '{print $1}')
           if [ -z "$nrn_branch" ]; then
               nrn_branch=master
           fi