Added some commentary and ensure that the cache directory exists

gitlab-ultimate.gitlab-ci.yml

@@ -17,14 +17,16 @@ include:
     DS_DISABLE_DIND: "true"
     SAST_DISABLE_DIND: "true"
 
+  # We need to make sure both directories exist, then we can copy files over
+  # Since it is a separate volume, mv offers no advantages. tar | tar, plus rm, is the fastest execution
   before_script:
-    - mkdir -p ~/.m2/repository
-    - cp -R $CI_PROJECT_DIR/.m2/repository/ ~/.m2/repository/
+    - mkdir -p ~/.m2 $CI_PROJECT_DIR/.m2
+    - tar -cC $CI_PROJECT_DIR/.m2 repository | tar -xC ~/.m2
     - rm -rf $CI_PROJECT_DIR/.m2/repository
 
+  # Copy the repository back to the cache area
   after_script:
-    - mkdir -p $CI_PROJECT_DIR/.m2/repository
-    - cp -R ~/.m2/repository/ $CI_PROJECT_DIR/.m2/repository/
+    - tar -cC ~/.m2 repository | tar -xC $CI_PROJECT_DIR/.m2
 
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