curl: NULL pointer dereference in libcurl URL API redirect_url() with CURLU_DEFAULT_SCHEME

Summary A NULL pointer dereference appears to exist in libcurl's URL API path when curlurlset handles a relative URL together with CURLUDEFAULTSCHEME on a CURLU handle that has host/path information but no stored u-scheme. The issue is in lib/urlapi.c inside redirecturl, where u-scheme is used in...