gitlab-ci.yml: Use CI_PROJECT_DIR instead of $(pwd) for cache

.gitlab-ci.yml

@@ -56,6 +56,8 @@ source_dist:
   stage: test
   variables:
     PYTEST_ADDOPTS: "--color=yes"
+    INTEGRATION_CACHE: "${CI_PROJECT_DIR}/cache/integration-cache"
+
   script:
   # Diagnostics
   - mount
@@ -64,8 +66,6 @@ source_dist:
   - useradd -Um buildstream
   - chown -R buildstream:buildstream .
 
-  - export INTEGRATION_CACHE="$(pwd)/cache/integration-cache"
-
   # Unpack and get into dist/buildstream
   - cd dist && ./unpack.sh
   - chown -R buildstream:buildstream buildstream
@@ -109,10 +109,9 @@ tests-unix:
   variables:
     BST_FORCE_BACKEND: "unix"
     PYTEST_ADDOPTS: "--color=yes"
+    INTEGRATION_CACHE: "${CI_PROJECT_DIR}/cache/integration-cache"
   script:
 
-    - export INTEGRATION_CACHE="$(pwd)/cache/integration-cache"
-
     # We remove the Bubblewrap and OSTree packages here so that we catch any
     # codepaths that try to use them. Removing OSTree causes fuse-libs to
     # disappear unless we mark it as user-installed.