Augmenting the PATH does not work like this in ci.yml, so do it in the test runner script.

.github/workflows/ci.yml

@@ -124,7 +124,6 @@ jobs:
       CCACHE_SLOPPINESS: "pch_defines,time_macros"
       CCACHE_COMPRESS: 1
       CCACHE_MAXSIZE: "250M"
-      PATH: "/usr/lib/ccache:$PATH"
 
     steps:
       - name: Checkout repo

Tools/ci-run.sh

@@ -81,6 +81,7 @@ fi
 
 # Run tests
 ccache -s 2>/dev/null || true
+export PATH="/usr/lib/ccache:$PATH"
 
 if [ "$COVERAGE" != "1" -a -n "${PYTHON_VERSION##pypy*}" ]; then
   CFLAGS="-O2 -ggdb -Wall -Wextra $(python -c 'import sys; print("-fno-strict-aliasing" if sys.version_info[0] == 2 else "")')" \