consider importability in exit code

pipelines/build.sh

@@ -46,11 +46,11 @@ coverage html
 echo "===================== importability ====================="
 echo " > try 'from $JOB_NAME.top_level_interface import *'"
 python -c "from $JOB_NAME.top_level_interface import *"
-if [ "$?" != 0 ]; then
-  import_status=$?
-  echo "Failed!"
+import_status=$?
+if [ "$import_status" != 0 ]; then
+  echo "Import failed!"
 else
-  echo "Done!"
+  echo "Import done!"
 fi
 
 # the exit value is determined from unit tests