Rm previous build only if exists

.gitlab-ci.yml

 before_script:
-  - export destdir=/tmp/bfpsinstall
-  - mkdir $destdir $destdir/lib/ $destdir/lib/python3.6/ $destdir/lib/python3.6/site-packages/
+  - export destdir=/tmp/bfpsinstall ||:
+  - mkdir $destdir $destdir/lib/ $destdir/lib/python3.6/ $destdir/lib/python3.6/site-packages/ ||:
   - export PYTHONPATH=$PYTHONPATH:$destdir/lib/python3.6/site-packages/
   - export PATH=$PATH:$destdir/bin/
 
@@ -18,8 +18,9 @@ simple-test:
     - mpi
     - python3
 
+
 after_script:
-  - rm obj/* 
-  - rm -r build/*
-  - rm -r $destdir
+  - rm obj/* ||:
+  - rm -r build/* ||:
+  - rm -r $destdir ||: