Compute BOOST_BRANCH

.github/workflows/ci.yml

@@ -34,8 +34,10 @@ jobs:
 
       - name: Setup
         run: |
+          REF=${GITHUB_BASE_REF:-$GITHUB_REF}
+          BOOST_BRANCH=develop && [ "$REF" == "master" ] && BOOST_BRANCH=master || true
           cd ..
-          git clone -b ${GITHUB_BASE_REF:-$GITHUB_REF} --depth 1 https://github.com/boostorg/boost.git boost-root
+          git clone -b $BOOST_BRANCH --depth 1 https://github.com/boostorg/boost.git boost-root
           cd boost-root
           cp -r $GITHUB_WORKSPACE/* libs/assert
           git submodule update --init tools/boostdep