Fix ccache saving on cache hit (#26)

See boostorg/boost-ci#166

.github/workflows/ci.yml

@@ -132,20 +132,23 @@ jobs:
             fi
             git config --global pack.threads 0
 
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
         with:
           # For coverage builds fetch the whole history, else only 1 commit using a 'fake ternary'
           fetch-depth: ${{ matrix.coverage && '0' || '1' }}
 
       - name: Cache ccache
-        uses: actions/cache@v2
+        uses: actions/cache@v3
         if: env.B2_USE_CCACHE
         with:
           path: ~/.ccache
-          key: ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}
+          key: ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}-${{github.sha}}
+          restore-keys: |
+            ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}-
+            ${{matrix.os}}-${{matrix.container}}-${{matrix.compiler}}
 
       - name: Fetch Boost.CI
-        uses: actions/checkout@v2
+        uses: actions/checkout@v3
         with:
           repository: boostorg/boost-ci
           ref: master