Only copy cleanup script if it has changed

src/freedombone-base-email

     git checkout $CLEANUP_MAILDIR_COMMIT -b $CLEANUP_MAILDIR_COMMIT
     set_completion_param "cleanup-maildir commit" "$CLEANUP_MAILDIR_COMMIT"
 
-    cp $INSTALL_DIR/cleanup-maildir/cleanup-maildir /usr/bin
+    if [ ! -f /usr/bin/cleanup-maildir ]; then
+        cp $INSTALL_DIR/cleanup-maildir/cleanup-maildir /usr/bin
+    else
+        HASH1=$(sha256sum $INSTALL_DIR/cleanup-maildir/cleanup-maildir | awk -F ' ' '{print $1}')
+        HASH2=$(sha256sum /usr/bin/cleanup-maildir | awk -F ' ' '{print $1}')
+        if [[ "$HASH1" != "$HASH2" ]]; then
+            cp $INSTALL_DIR/cleanup-maildir/cleanup-maildir /usr/bin
+        fi
+    fi
 
     mark_completed $FUNCNAME
 }