Fix zconfig_chunk_save's abort and save the tree instead of the first entry.

Hello,

This is the patch i wrote to fix my problem I reported in #469. 
I didn't test it much, but it seems to work for me.

I am not sure the removal of `&& !rc` from `s_config_execute()` loop doesn't break something else as I don't know enough about the implementation. At least it doesn't seem to.