Fix branch checkout for PRs with GitHub workflow

.github/workflows/cicd.yml

@@ -6,6 +6,7 @@ on:
       - master
       - 'WIP**'
       - '4.*'
+      - 'CURA-*'
   pull_request:
 jobs:
   build:

docker/build.sh

@@ -17,24 +17,40 @@ cd "${PROJECT_DIR}"
 # Clone Uranium and set PYTHONPATH first
 #
 
-# Check the branch to use:
-#  1. Use the Uranium branch with the branch same if it exists.
-#  2. Otherwise, use the default branch name "master"
+# Check the branch to use for Uranium.
+# It tries the following branch names and uses the first one that's available.
+#  - GITHUB_HEAD_REF: the branch name of a PR. If it's not a PR, it will be empty.
+#  - GITHUB_BASE_REF: the branch a PR is based on. If it's not a PR, it will be empty.
+#  - GITHUB_REF:      the branch name if it's a branch on the repository;
+#                     refs/pull/123/merge if it's a pull_request.
+#  - master:          the master branch. It should always exist.
+
+# For debugging.
 echo "GITHUB_REF: ${GITHUB_REF}"
+echo "GITHUB_HEAD_REF: ${GITHUB_HEAD_REF}"
 echo "GITHUB_BASE_REF: ${GITHUB_BASE_REF}"
 
-GIT_REF_NAME="${GITHUB_REF}"
-if [ -n "${GITHUB_BASE_REF}" ]; then
-  GIT_REF_NAME="${GITHUB_BASE_REF}"
-fi
-GIT_REF_NAME="$(basename "${GIT_REF_NAME}")"
-
-URANIUM_BRANCH="${GIT_REF_NAME:-master}"
-output="$(git ls-remote --heads https://github.com/Ultimaker/Uranium.git "${URANIUM_BRANCH}")"
-if [ -z "${output}" ]; then
-    echo "Could not find Uranium banch ${URANIUM_BRANCH}, fallback to use master."
-    URANIUM_BRANCH="master"
-fi
+GIT_REF_NAME_LIST=( "${GITHUB_HEAD_REF}" "${GITHUB_BASE_REF}" "${GITHUB_REF}" "master" )
+for git_ref_name in "${GIT_REF_NAME_LIST[@]}"
+do
+  if [ -z "${git_ref_name}" ]; then
+    continue
+  fi
+  git_ref_name="$(basename "${git_ref_name}")"
+  # Skip refs/pull/1234/merge as pull requests use it as GITHUB_REF
+  if [[ "${git_ref_name}" == "merge" ]]; then
+    echo "Skip [${git_ref_name}]"
+    continue
+  fi
+  URANIUM_BRANCH="${git_ref_name}"
+  output="$(git ls-remote --heads https://github.com/Ultimaker/Uranium.git "${URANIUM_BRANCH}")"
+  if [ -n "${output}" ]; then
+    echo "Found Uranium branch [${URANIUM_BRANCH}]."
+    break
+  else
+    echo "Could not find Uranium banch [${URANIUM_BRANCH}], try next."
+  fi
+done
 
 echo "Using Uranium branch ${URANIUM_BRANCH} ..."
 git clone --depth=1 -b "${URANIUM_BRANCH}" https://github.com/Ultimaker/Uranium.git "${PROJECT_DIR}"/Uranium