nginx-combined-upstreams-module version 1.2

Bugfix: adjust pointers to last elements in lists when copying headers of the subrequest.

Details: when copying objects of type ngx_list_t, pointers last must point to part if there is only one part in the list, otherwise further additions to the target list may affect only the source list. Particularly, gzip module may add a Content-Encoding header which, in case of failure, may break HTTP response as the response body will still be gzipped.