Hello,

I noticed that curl_easy_duphandle does not necessarily duplicates the
CURLOPT_COOKIEFILE option. It only enables the cookie engine in the
destination handle if data->cookies is not NULL (where data is the
source handle). In case of a new initialized handle which just had the
cookie support enabled by a curl_easy_setopt(handle, CURL_COOKIEFILE,
"")-call, handle->cookies is still NULL because the setopt-call only
appends the value to data->change.cookielist, hence duplicating this
handle will not have the cookie engine switched on. Attached is a patch
against version 7.19.4 which will additionally duplicate
data->change.cookielist if not NULL.

Ciao, Frank