CI: inc: build.yml: Only mount mirrors if not already mounted/mapped

ci/inc/build.yml

@@ -33,8 +33,11 @@ variables:
   # mirrors is desired.
   #
   cache:
-    - sudo mkdir /mirrors
-    - sudo mount -t cifs -o username=${CI_SMB_USER},password=${CI_SMB_PWD},${CI_SMB_OPTS} //${KED_GITLAB_HOST_ADDR}/mirrors/develop /mirrors
+    - |
+      if ! test -d /mirrors; then
+        sudo mkdir /mirrors
+        sudo mount -t cifs -o username=${CI_SMB_USER},password=${CI_SMB_PWD},${CI_SMB_OPTS} //${KED_GITLAB_HOST_ADDR}/mirrors/develop /mirrors
+      fi
     - mkdir -p build
     - ln -s /mirrors/sources build/downloads
     - ln -s /mirrors/sstate build/sstate-cache